Connolly (still eligible at 22) has not featured for Jim Crawford's side in qualifying so far as he had been involved in with the senior set-up, but has yet to score a senior international goal in his eight caps to date, the last of which came in January 2021.
"Aaron, with regards international football, has been a little bit of driftwood where he wasn't with the senior team or the 21s," said Crawford.
"He can score goals, he's a real threat, so to have him with the 21s for this game is great. For himself, it’s a chance to show people that he is still around and that he can produce in big games. And that’s what this play-off is, it’s a fantastic stage for him to be involved in."
"He done an interview a number of weeks ago which I looked at and he showed a level of maturity, he seemed remorseful with regards to how he behaved, whether it was at Brighton or what have you.
"It was something that got me thinking. I got somebody involved in the process to link in with him and just ask if he would be interested to play with the 21s. the answer I got back was 'yeah, certainly’. He wants to put on a green shirt again.
"That was a fantastic start."
Since leaving Brighton for pastures new in Venice at Serie B club Venezia, the Galwegian has appeared in five league games but has yet to find the net.
"I rang Aaron a few times, we’ve had conversations, we had a Zoom call yesterday. I just think it was important to stress to him and underline to him what got us to the play-offs.
"The group of players we have got have been fantastic up to now, but I think we all know what Aaron can bring to any squad."
Connolly's professionalism has been questioned by those within the game but has now been given a chance to rectify his international career, albeit at under-21 level.
"We can’t neglect players of that talent and ability and cast them aside. It’s an opportunity for him to prove his worth that he wants to play for the Republic of Ireland – and here’s a great platform and stage for him to show Stephen that he’s ready to go back to the senior team. [The] players in the under-21 squad can learn from that."
Currently, Crawford's reign at the helm of the under-21 operation comes to an end after the play-off game away to Israel. A new contract is yet to be signed, but he insisted that all focus was on getting an Irish under-21 men's team to their first ever major tournament.
"[We are] still negotiating, that's where we are at," said Crawford.
"I just have the ability to be focused on this under-21s game. That’s where my focus is and I have a real narrow focus on that at the minute. I’m sure it will get done sooner rather than later but at this moment in time I am concentrating on these two games coming up."
Asked on whether he was frustrated by the deal not be concluded before coming into an international camp.
"Look in an ideal world yes you’d like it done but it’s not and these things happen in life. You’re negotiating and it’s certainly not going to bother me.
"These games are too big to be worried about that. I know something is going to get done. I am confident we can come to an agreement but at this stage nothing has been done.
"But I’ve parked that up now, there is other people dealing with it at this point in time. Nothing is going to get in my way in preparing for Israel."
One major blow for Crawford's side is that midfielder Gavin Kilkenny is ruled out through injury.
Currently on loan at Stoke City, Kilkenny has started all but one of the group games so far but has picked up a grade two tear in his knee and will miss the upcoming play-off games.
St. Patrick's Athletic captain Joe Redmond takes his place in the squad as Oisín McEntee is ruled out after picking up an injury in the home win against Bosnia and Herzegovina.
One time senior call-up Luca Connell has also returned to the fold after leaving a horror spell at Celtic to go and play for Barnsley in the English League One.
"With Luca, he was with Celtic at the time, he went on loan to a team in the third tier in Scotland. I just didn't think that that was great for his development and he agreed. He was able to turn everything around when he went to Barnsley, he is playing every week.
"I went to see him play against Ipswich who are top of the league in league one and he done really well. He’s got a fantastic left foot, he is a great passer of the ball, he is aggressive and again he has another player that I think had he been with Barnsley a lot earlier he would have been involved in our squads a lot more.
"He is over the moon to be involved. Both his grandparents are from Dublin and I do know that his Nan will be exceptionally proud he’s part of the under-21s international game against Israel."
Udinese's Festy Ebosele has also dropped down from the senior squad to the under-21 squad in which will be a boost for Crawford's selection.
The first leg of the play-offs will take place at Tallaght Stadium on Friday, 23 September, where more than 7,000 have already secured their seat for the game. The second leg is scheduled for Bloomfield Stadium, Tel Aviv, Israel on Tuesday, 27 September.
Republic of Ireland senior men's under-21 squad
Goalkeepers: David Harrington (Cork City), Brian Maher (Derry City), Luke McNicholas (Sligo Rovers)
Defenders: Eiran Cashin (Derby County), Festy Ebosele (Udinese), Andy Lyons (Shamrock Rovers), Mark McGuinness (Sheffield Wednesday, on loan from Cardiff City), Jake O'Brien (RWD Molenbeek, on loan from Crystal Palace), Lee O'Connor (Tranmere Rovers), Joe Redmond (St. Patrick’s Athletic), Sean Roughan (Lincoln City)
Midfielders: Finn Azaz (Plymouth Argyle, on loan from Aston Villa), Luca Connell (Barnsley), Conor Coventry (West Ham United), Dawson Devoy (MK Dons), Joe Hodge (Wolves), Will Smallbone (Stoke City, on loan from Southampton), Ross Tierney (Motherwell)
Forwards: Aaron Connolly (Venezia, on loan from Brighton & Hove Albion), Evan Ferguson (Brighton & Hove Albion), Joshua 'JJ’ Kayode (MK Dons, on loan from Rotherham United), Liam Kerrigan (Como 1907), Ollie O’Neill (Fulham), Mipo Odubeko (Port Vale, on loan from West Ham United), Tyreik Wright (Bradford City, on loan from Aston Villa)