Martin O’Neill has had a string of well-documented problems throughout his tenure as Ireland manager, and while not quite as many as Jay-Z's 99, there is one particular issue that has been there since the start, and has yet to be resolved.

The clue to this particular conundrum is abundantly clear when you look at the goals-scored column throughout the five years since O’Neill took the reins of the Ireland senior side.

The 19 goals scored over the ten games of O’Neill’s first qualifying campaign for Euro 2016 may appear a decent return for an international side, however, once the 11 Gibraltar giveaways are discounted, the statistics reveal a bleaker story.

The stats are even more stark for the 2018 World Cup qualifiers, once the Moldovan five are subtracted, as Ireland managed less than a goal a game and produced a paltry two goals at home against the remaining four nations in the group.

"I inherited a rather older Robbie Keane than I would like to have done," lamented O'Neill, once again bemoaning the fact that he has yet to unearth a natural goalscorer. "But he's the only one that you could rely on to actually score goals.

"I have had this problem with the national side here for five years.

"Jon Walters took on that mantle during the Euro qualifying and that was great, but you wouldn't have said that Jon was a prolific goalscorer in that sense, certainly not in the way that Robbie Keane is."

The search goes on. 

O'Neill is left with five front men in his squad for the upcoming encounters with Denmark and Wales, one of which, Callum Robinson, is more effective playing in a wide role, cutting in off either flank, while Shane Long is struggling with an injury and sat out the first day's session ahead of the double header.

Long has scored some vital goals for his country and brings passion and enthusiasm by the bucket-load, however the striker has never been prolific in front of goal and his club statistics emphasise that over the past few seasons.

"Shane hasn't scored at club level now for quite some considerable time, and of course that plays with your mind," said O'Neill when asked about whether the player can still have an impact at international level.

Aiden O'Brien pushed himself up the pecking order following an excellent display in the recent international friendly in Poland, leading the line and scoring the Ireland goal in the 1-1 draw.

The Millwall centre-forward has not been able to hold down a regular place at his club this season, however, O'Neill was impressed by the player in Poland and does not always choose his team based on club form alone.

"Sometimes the players who do well for us and find themselves out of the shadows in the first team at their club," said O'Neill.

"For instance, young Aiden O'Brien did well in the game against Poland, worked exceptionally hard and got a goal for his rewards and comes back to find himself sometimes starting, sometimes on the bench for Millwall, so it will be a wee bit frustrating.

"I think he should not concern himself too much with what's happened in the last couple of weeks at club level and try to concentrate and try to think about the good things he did in the game in Poland."

Two natural goal scorers who have been called into the squad for the sole purpose of attempting to bring goals into the team are Aston Villa's Scott Hogan and Sean Maguire, now at Preston, who really caught the manager's eye during his free-scoring final days at Cork City.

Hogan earned himself a big money move to Aston Villa following a great spell in front of goal with Brentford, yet his career at the Championship club has been slow to ignite, while his Ireland opportunities have been few and far between.

Another who is struggling to nail down a regular first-team place at club level, Hogan believes he can make his mark with Ireland if afforded the opportunity to lead the line.

"It’s difficult, obviously," admitted Hogan when asked who can fill Robbie Keane's boots.

"When someone scores that many goals, it’s a hard act to follow. You’ve just got to do what you can, believe in what you’re good at and hopefully, you get given opportunities to take your chance."

"You’ve just to concentrate on yourself. What’s gone is gone. He is a hard act to follow, maybe impossible to follow, but you just have to take each game as it comes and hopefully get halfway near the level someone sets."

Sean Maguire moved from the League of Ireland to the English Championship and immediately made his mark at Preston, helping the Deepdale side to a seventh-place finish in the league last season.

However, Maguire's progress for both club and country has been severely hampered by a string of injuries, which has caused him to miss large chunks over the past 12 months.

The striker made a welcome return to Preston at the weekend and played the final 15 minutes, helping to create his side's final goal in their 4-0 victory.

And Maguire appears keen to get involved over the next two games to stake a claim for that striker's jersey heading into the Euro 2020 qualifiers in 2019.

"We haven’t had that goalscorer since Robbie Keane left," said Maguire.

"I don’t think we will ever fully replace him, given the number of goals he has scored for his country. I feel there is an opportunity for one of the four new lads coming in to stake a claim for a jersey.

"If I get the opportunity, hopefully, I do step up to the plate and play a crucial part, if that’s coming off the bench or from the start of the game, we’ll see what happens."

O'Neill will leave it late, of course, before he names his side to face Denmark on Saturday, and with no obvious striking starter in the squad, the manager will be looking closely at training to see who is playing with real confidence.

Millwall's O'Brien is the man to dislodge, you would think, considering he scored on his last outing in green, yet you get the impression that O'Neill would love to launch Maguire into the mix to see what he can deliver at this level.

"Remember he only came on in the last 15 minutes of the match and that was his first piece of action for quite some time," said O'Neill, when asked about how much Maguire can contribute this week.

"We'll have a look at him and if he can make a little cameo for us that would be great."

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