It isn't all that long since Ireland started a World Cup qualifying campaign in Belgrade.

In fact, it's just one tournament cycle ago. On 5 September 2016, the Boys in Green started on the road to Russia 2018 off the back of an encouraging Euro 2016 showing.

A 2-2 draw with top seeds Serbia that night provided some encouragement, especially in light of Martin O'Neill's side being comprehensively outplayed by the hosts. 

Unfortunately, while the journey did continue on to a play-off courtesy of a famous win in Cardiff, the 5-1 loss to Denmark in November 2017 remains one of the darkest days in our football history.

Fast forward to this week and much has changed for Ireland when it comes to the make-up of the squad and indeed the management team.

Stephen Kenny has named a 29-man squad for the trip to Serbia, the visit of Luxembourg and the friendly against Qatar, that is replete with inexperienced names.

That's partly due to injury but also points to where the playing pool is at currently, with some regulars either out of favour or out of form at club level.

Which makes it all the more difficult to name a nailed-on starting XI. So how would the team line-up based on recent club form and fitness levels?

GOALKEEPER

Darren Randolph would have been the definite pick if fit, even though he only makes sporadic appearances for West Ham.

But the long-time number one is absent with a hip injury, leaving Kenny to name four options in his squad: Caoimhin KelleherGavin Bazunu, Mark Travers and Kieran O'Hara.

Between them, that quartet have four senior caps, with Bournemouth's Travers and Burton Albion's O'Hara splitting those appearances with two each. However, none of those caps were won in competitive games and in fact, were as a result of appearances in the same two friendly matches against Bulgaria and New Zealand in 2019, with Travers starting one game and coming in as a sub in the other, and vice versa for O'Hara.

Kieran O'Hara, right, and Mark Travers during the 2019 friendly against New Zealand

When it comes to club form this season, neither goalkeeper has been getting enough game-time of late. O'Hara was Burton's number one for a long stretch after the season started, but he has been on the bench for the League One club in every game since 2 January when he made the last of his 17 appearances in all competitions in a 5-1 loss to Oxford United.

Travers, meanwhile, had been getting starts after Bournemouth loaned him out to Swindon in January. It was a good move in the sense that he played the full 90 minutes eight times after the drop-down to League One in a short space of time.

But with the Cherries experiencing injury issues in goal last month, the Kildare native was recalled as cover and has since been rooted firmly to the bench behind Asmir Begovic, including in the FA Cup against Southampton on Saturday.

So it's former Shamrock Rovers keeper Bazunu who has made the most appearances this season, featuring 30 times in all competitions for Rochdale in League One.

Still only 19, the Manchester City loanee has acquitted himself well ahead of this weekend, although clean sheets have been at a premium in a struggling Rochdale side.

Caoimhin Kelleher and Gavin Bazunu with the U21s in 2019

However, if Kelleher is able to shake off his current fitness concerns, the level he has played at in his handful of Liverpool appearances would push the Corkman top of the queue.

The 22-year-old might have only played a sixth of the games Bazunu has this season but two of his five games were in the Champions League where he performed strongly including an excellent save against Ajax in a clean-sheet performance, while he only conceded once in two Premier League appearances. 

The downside is Kelleher has only made two appearances in this calendar year, which came in the FA Cup in a 4-1 win over what was essentially an Aston Villa youth team and against Brighton in a 1-0 home defeat at the start of February.

But the fact that a manager of Jurgen Klopp's standing has entrusted the young Irishman with starts when established number one Alisson Becker is unavailable is a huge vote of confidence and, given that Kenny has no fear of blooding youth, Kelleher's club showings may well be enough to persuade the Irish manager to throw him into the deep end - provided he is fit.

Goalkeeper: Caoimhin Kelleher.

DEFENCE

While some of Ireland's players have been more accustomed to playing in a back three at club level, Kenny has tended to go with a back four thus far, so one can't envisage that changing in Belgrade all of a sudden.

That means Seamus Coleman, Matt Doherty and Cyrus Christie are battling for the right-back spot.

Although Christie has been a regular for Chris Hughton's Nottingham Forest, he is certainly behind Coleman and Doherty in the pecking order.

Doherty, however, has struggled at times since switching from the comfort of a wing-back role in Wolves' back five to the four of Jose Mourinho's Tottenham. 

While the 29-year-old has found himself back in favour since February - at least in comparison to his Spurs rival Serge Aurier - his performances have not been of the outstanding vintage of recent campaigns, although that would also be a reflection of the form of many of his club team-mates.

Coleman had fallen behind Doherty at international level but the Ireland captain has enjoyed an upturn in form for Everton, albeit in a campaign that has featured some injury absences.

Coleman came close to scoring in the Merseyside derby

The 32-year-old did suffer a fitness setback after captaining the Toffees to a rare derby win over Liverpool on 20 February in a fine individual display and only returned to first-team action last weekend as a substitute against Burnley before being named to start in the FA Cup against Manchester City on Saturday evening.

He has made one more PL appearance (16) compared to Doherty but the latter has also featured in the Europa League and has had more game-time in the last few weeks.

It's a tight one but the pick at right-back is Coleman based on overall form and confidence levels during the campaign when he has been available.

Meanwhile, there is more uncertainty in central defence than back in the autumn in light of John Egan's injury. Shane Duffy had already started to struggle after his move to Celtic but the nightmare individual form has not improved since then as the Hoops' 10-in-a-row bid fell flat. He has also not played in the Scottish Premiership since mid-February as youngster Stephen Welsh has leapfrogged him in the pecking order.

Duffy has tended to be the automatic pick at centre-back for Ireland since 2016 but besides his own form, there are viable rivals to step in ahead of him.

Dara O'Shea has stood up well for West Brom in a difficult Premier League campaign for the Baggies. 

The versatile 22-year-old has made 22 league appearances for the club this season, earning the trust of both Slaven Bilic and Sam Allardyce, while he had already broken into the Ireland starting side under Kenny.

Ciaran Clark has also been involved in a struggling side but has been one of the more consistent and reliable performers for Newcastle of late, starting their last five league games up to mid-March after an injury ravaged start to the campaign.

Burnley's Kevin Long has plenty of international minutes behind him, but at club level his appearances come in waves and it's always dependent on whether one of the Clarets' main centre-back pairing of James Tarkowski and Ben Mee are absent. At the start of the season, he consequently saw more game-time but since the latter two have been re-established, Long has made just two league appearances in this calendar year, having to content himself to providing cover from the bench.

Dara O'Shea has been a West Brom lynchpin this season

The trend of an Irish player featuring in a struggling club side doesn't end with some of the aforementioned names as Enda Stevens has found himself in a similar predicament at Sheffield United, which is a stark contrast to last season.

However, the left-sided defender remains an automatic pick in the Blades team when fit, which is in contrast to Ryan Manning at Championship side Swansea. The Galwegian has been getting far more minutes in this month compared to earlier in the season but Stevens still leads the way overall.

Back four: Seamus Coleman, Dara O'Shea, Ciaran Clark, Enda Stevens.

MIDFIELD

Based purely on club form, there are some standout options in midfield for Kenny to consider. Conor Hourihane, who has tended to play deeper at international level, has thrived in a more advanced role for Swansea since moving there on loan in January.

The 30-year-old has weighed in with five goals in 13 Championship appearances over the last two months and was already a regular under Kenny.

But there is a major asterisk beside his name now after he was forced off after just 18 minutes as Swansea lost to Mick McCarthy's Cardiff City on Saturday, as he emerged as a late doubt, which is clearly a body blow for Kenny given the player's form and experience.

It has also been a breakout season for Jason Knight at Derby County with a leadership ability belying his youth per his manager Wayne Rooney.

Linked with Premier League clubs, the 20-year-old Dubliner has been a regular at the heart of the Rams midfield and even captained the side in January. He was also a favourite of Kenny's in the Under-21 set-up and has already made his Ireland senior debut.

Josh Cullen has impressed at Anderlecht

While slightly out-of-sight in Belgium, Josh Cullen has been impressing for Anderlecht this season. The 24-year-old has been getting regular game-time for the country's biggest club - albeit as they rebuild after a downturn in fortunes - and in an interview with the Examiner, the former West Ham midfielder indicated that Kenny has been impressed with what he has been producing, particularly on the ball.

Another steady option with more international experience is Preston North End captain Alan Browne, who has barely missed action this season, weighing in with 32 appearances and three goals for the Championship side, before a red card against Middlesbrough on 16 March.

Jayson Molumby was promoted to the Irish senior side after Kenny took charge but struggled for game-time in the first half of the campaign at Brighton. Indeed, Graham Potter only afforded him a one-minute run-out in the Premier League last November.

Since joining Browne on loan at Preston, he has been able to up those minutes, although he did find himself rooted to the bench for a couple of games this month as well as Saturday when North End lost to Luton.

Jeff Hendrick, whose last Ireland appearance ended with a red card against Wales in the Nations League, has plenty of Premier League and international experience and has been a regular in the Newcastle side, although his involvement has tailed off since he was sent off against Southampton in February.

A 57-minute appearance against West Brom had been his only minutes in the league until he replaced the injured Isaac Hayden in first-half stoppage time against Brighton on Saturday, with the former Derby midfielder not being used off the bench otherwise by Steve Bruce. 

His former St Kevin's Boys team-mate Robbie Brady could conceivably feature as an option on one of the flanks as well as in midfield but, like Hendrick, he has been in-and-out at club level for Burnley.

Between early December and late January, the 29-year-old was trusted with regular starts by Sean Dyche but he has only played a total of 89 minutes since early February, with injuries a factor.

Midfield: Conor Hourihane* (Alan Browne if the Swansea man is unavailable), Jason Knight, Josh Cullen.

ATTACK

Basing this on form means the front three will not be the most tactically balanced, especially as Kenny does not have his favoured central option Adam Idah available due to injury. In any case, the Norwich forward has only had sporadic minutes off the bench for the Championship high-flyers since returning from a knee injury at the end of January.

As for the wide options if Brady is not included, the Ireland boss has James McClean, Daryl Horgan, Ronan Curtis, Callum O'DowdaCallum Robinson and Aaron Connolly to choose from, with the latter two nominally playing at the highest level in England.

Aaron Connolly in action against Burnley on 6 February

The injury and match-fitness jinx that Kenny has had to deal with is particularly evident in that sector of the squad. McClean had not played for a month before being named in the squad due to a foot injury and his Stoke boss Micheal O'Neill had deemed him "not fit enough to be part of the squad".

O'Dowda only returned to training with Bristol City on 1 March after nine weeks out and has been trying to regain his fitness with substitute appearances against Birmingham and Blackburn - a total of 40 minutes - before the Ireland squad was named on Thursday, scoring in the former match. He then started on Saturday as Bristol lost to Rotherham. But he was then forced off on 88 minutes, as he emerges as a doubt for the upcoming qualifiers.

Connolly, who would be a nailed-on starter if fit, has been nursing a rib injury and was a major doubt before being included in the squad. He has been in and out of the Brighton team but does come with Premier League experience, although he has only scored twice in the top flight this campaign. 

Frustratingly, he started the New Year off with a bang after scoring against Wolves only to suffer a muscular injury minutes later and that's one of five appearances since the start of 2021. Given that his club manager Potter was suggesting that he would only be fit after the international break, the qualifiers might come too soon for him in spite of his inclusion.

In contrast, his fellow Galway native Horgan has been getting plenty of game-time in the Championship with Wycombe and has only missed three of their league games. Given that he was a regular option for Kenny in the Nations League, the winger is in a good position to start on the flank.

Similarly, Curtis has been a front-line option for Portsmouth in League One, primarily off the left, and has weighed in with 10 goals in all competitions, including six in the league and four assists. The goals have dried up since early February however, although the fact that he got Nations League minutes and started the Bulgaria game may well stand in his favour due to the injury worries over other options like Connolly. That and his versatility and ability to play across the front three.

Troy Parrott rounds Plymouth's Mike Cooper to score on 13 March

Robinson has been back in the Premier League this season with West Brom but since he last featured against former club Sheffield United on 2 February, the similarly versatile forward has not been sprung from the bench once by Allardyce. He hasn't scored in the league since an excellent brace against Chelsea in September either.

Which brings us to the trio of more central options in the shape of James Collins, Troy Parrott and Shane Long. The latter is undoubtedly the most experienced of the three and has dropped down to the Championship with Bournemouth on deadline day to get more minutes. Two goals have followed in eight games but while he has got his fair share of game-time, he hasn't been a nailed-on starter every week.

Parrott is the youngest of the three by some distance but the 19-year-old Tottenham loanee did take a while to notch his first goal of the season.

An injury-affected loan at Millwall meant he never really got going in the first half of the campaign, so Spurs sent him out to Ipswich in January and he has been a regular starter in League One. 

Most recently, he had played as a second striker rather than up top and the wait for a goal ran into his 11th appearance before coming last weekend in a 1-0 win over Plymouth.

Luton's Collins has played the most of the three across the campaign with 10 goals in 32 appearances for the Championship club including a hat-trick against Preston in December and another against Norwich in the Carabao Cup six months ago.

And like a few other squad members, the goals have dried up in the last number of weeks. His last goal was at home to Huddersfield in early February and he has been in and out of the starting line-up in the nine league games since, for example coming off the bench with 23 minutes to go this weekend. But he is the highest-scoring Irish centre-forward in the squad at club level this season.

Attack: Daryl Horgan, James Collins, Ronan Curtis.

Ireland's XI (4-3-3):

Kelleher

Coleman, O'Shea, Clark, Stevens

Knight, Cullen, Hourihane* (Browne)

Horgan, Collins, Curtis.

Republic of Ireland squad:

Goalkeepers: Caoimhin Kelleher (Liverpool), Gavin Bazunu (Rochdale, on loan from Manchester City), Mark Travers (AFC Bournemouth), Kieran O'Hara (Burton Albion).

Defenders: Seamus Coleman (Everton), Matt Doherty (Tottenham Hotspur), Shane Duffy (Celtic, on loan from Brighton and Hove Albion), Enda Stevens (Sheffield United), Kevin Long (Burnley), Ciaran Clark (Newcastle United), Dara O'Shea (West Bromwich Albion), Ryan Manning (Swansea City), Cyrus Christie (Nottingham Forest).

Midfielders: Conor Hourihane (Swansea City, on loan from Aston Villa), Alan Browne (Preston North End), Jeff Hendrick (Newcastle United), Jayson Molumby (Preston North End, on loan from Brighton and Hove Albion), Jason Knight (Derby County), Josh Cullen (Anderlecht).Wingers: Robbie Brady (Burnley), James McClean (Stoke City), Daryl Horgan (Wycombe Wanderers), Ronan Curtis (Portsmouth), Callum O'Dowda (Bristol City).

Strikers: Callum Robinson (West Bromwich Albion), Aaron Connolly (Brighton and Hove Albion), Shane Long (AFC Bournemouth, on loan from Southampton), James Collins (Luton Town), Troy Parrott (Ipswich Town, on loan from Tottenham Hotspur).

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