Martin O’Neill has some big decisions to make ahead of tomorrow night’s clash with Denmark, but the manager will be delighted that he has a fully fit squad to choose from.

Aside from keeper Rob Elliot’s withdrawal for personal reasons, everyone else trained at Abbotstown this morning, and while the starting XI for the return fixture (7.45pm, live on RTÉ2) will have a very familiar look to it, there will certainly be changes in both personnel and tactics.

David Meyler obviously missed out in Copenhagen through suspension and is set to make a return to the side, playing in that holding role in front of the back four.

David Meyler at Tuesday's training session

But the manager was quick to admit following the first leg that his side would need to be more creative in the Dublin decider, and that could indicate that O’Neill will put faith in Wes Hoolahan to set the tempo for an attack-minded performance.

O’Neill, of course, named many attacking players in the team for the Copenhagen clash, yet they were unable to assert their influence in the game as Ireland spent most of the match on the back foot.

Hoolahan can instil confidence in those around him and allow Ireland to retain possession and influence in the opposition half.

"I think we will try to be that bit more expansive if we can and deal with the ball a wee bit better," said O’Neill at this afternoon’s press conference.

"We are going to try to win the game and will try to find a way to win it."

O'Neill spoke to a packed pressroom at the Aviva

And the manager knows that Hoolahan is the player that best fits those criteria to take the game to Denmark and attempt to win the match.

But should Hoolahan play, the manager will have to mould his team around the Norwich midfielder, which will result in a complete change to the formation, compared to Saturday’s match.

Hoolahan can either be employed in the number ten role in a straightforward 4-4-2 formation, or if the manager was really to take the game to Denmark, he could also be placed at the top of the diamond, allowing for two players up top.

O’Neill tends to throw caution to the wind when the win is required and in Lille at Euro 2016, the manager played a 4-1-3-2 formation with James McCarthy playing the holding role.

There was no Hoolahan in the team that day but O’Neill could recreate that same approach with Meyler sitting in behing James McClean, Robbie Brady and Jeff Hendrick, with Shane Long and Daryl Murphy in attack.

What is certain is that the manager will keep faith in his back five of Darren Randolph in goal, following his man of the match performance in Denmark, while Cyrus Christie, Shane Duffy, Ciaran Clark and Stephen Ward will marshal the defence.

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So what will O’Neill opt for to start the match tomorrow night?

The three-day turnaround is going to have some influence in the manager’s thoughts and for that reason, O’Neill may leave Murphy on the bench and hand Long the start, adding energy to the side in attack.

Should Hoolahan start in that number 10 role, the manager is left with a big decision on the trio to work alongside Meyler in midfield.

James McClean will surely sit on the left side of whatever midfield formation O’Neill opts for, while Robbie Brady will probably just get the nod to move back outside in place of Callum O’Dowda.

Which leaves Harry Arter and Jeff Hendrick fighting for that solitary spot in the middle of the park.

Choosing Hendrick would add to the attacking nature of the formation, however, Arter put in a terrific shift on Saturday night and the pragmatic O’Neill will surely err on the side of caution and not expect Meyler to patrol that area against a dynamic Danish midfield by himself.

Hendrick was struggling with his fitness in the build-up to Saturday’s game, so whether or not the Burnley man starts is probably the manager’s biggest decision ahead of the second leg.

Of course, the former Celtic and Leicester boss might want Hendrick’s attacking influence in his side, but if that is the case, it must be in place of Hoolahan.

The manager has started to edge the older players out of the mix in recent games with John O’Shea and Glenn Whelan playing a much lessened role in this side.

Hoolahan also belongs in that elder statesmen bracket and perhaps the manager believes that it is time his team stands up without relying on the Wes factor.

Watch Republic of Ireland v Denmark live on RTÉ 2 and the RTÉ Player from 7pm, coverage on RTÉ 2fm's Game On from 7pm, live blog on RTÉ Sport Online from 7pm