Ireland manager Martin O’Neill will be forced to make changes to his side as Callum O’Dowda has been ruled out of tomorrow night’s clash with Wales at the Aviva Stadium.

The Bristol City midfielder was substituted at half-time in Saturday’s Nations League encounter with Denmark and has been ruled out of the game with Wales as a ‘precautionary matter’.

The midfielder felt dizzy during the first half of the 0-0 draw with the Danes and while it would suggest a knock to the head, the player does not recall at what stage such an incident might have happened.

"We are trying to find out ourselves," admitted the manager, speaking at today’s pre-match press conference at the FAI headquarters.

"He is out of the game tomorrow night, precautionary, as much as anything else.

"He wasn’t feeling great at half-time, but he can’t remember when it actually happened during the course of the game."

The manager also hinted that he might make formation changes ahead of the visit of Ryan Giggs’ side, potentially reverting to a flat back four.

"We’ll get someone else into his position. Obviously, we’ll have a look at it and see whether we stay with the same system or go back to a back four, we’ll see.

"Overall, I think the players don’t mind the system and I think they quite enjoy it.

"And they are prepared for both, depending on which we decide to play."