We've been waiting months for this night to arrive, what with the will he/won't he over Gareth Bale's fitness, and the sudden injury crisis for Martin O'Neill to navigate, but it's finally time for what we knew would be the standout fixture in Group D.
A win will put Ireland a staggering seven points clear of Wales at the half-way stage in group fixtures, so Chris Coleman has picked his side in the knowledge that while it may not exactly be 'win or bust', a loss would be seriously damaging to their hopes of progressing.
The big news for Ireland is that James McCarthy has been passed fit to start and is in the side.
Here is the starting XI for the Republic of Ireland to take on Wales:
— FAIreland (@FAIreland) March 24, 2017
Ireland Subs: Westwood (GK), C. Doyle (GK), McGeady, K. Doyle, Horgan, Christie, Egan, Hourihane, Meyler, Hayes, O'Dowda, Pearce. #COYBIG
— FAIreland ⚽️🇮🇪 (@FAIreland) March 24, 2017