James McClean will miss the Republic of Ireland's opening Nations League fixture against Wales and friendly in Poland after undergoing surgery on his wrist.
The 29-year-old Stoke winger revealed the damage, which happened in training in Abbotstown on Tuesday morning, in an Instagram post showing photographs of his bandaged arm.
McClean's misfortune was later confirmed by the Football Association of Ireland.
A statement said: "Winger James McClean suffered a wrist injury during training and, after being assessed by the FAI medical team, he was brought to hospital for an x-ray and immediate surgery.
"McClean will miss the games against Wales and Poland."
The news will have come as a fresh blow to manager Martin O'Neill, who has already seen his options significantly reduced by injuries to Robbie Brady, James McCarthy, Shane Long, Scott Hogan and Sean Maguire.
Declan Rice and Harry Arter are also missing from the squad with the former mulling over an approach from native country England and the latter having withdrawn following a summer disagreement with assistant manager Roy Keane.
O'Neill was at least able to welcome striker Jonathan Walters back into the fold on Tuesday morning with he and Kristiansund BK keeper Sean McDermott training after meeting up with the squad following their club commitments, while Shane Duffy and David Meyler, who were rested on Monday, were also involved.
The statement added: "The Republic of Ireland squad took part in training at the FAI National Training Centre on Tuesday morning ahead of the departure to Cardiff for this week's UEFA Nations League game with Wales.
"Defender Shane Duffy (groin) and midfielder David Meyler (knee) sat out training on Monday, but both players were involved in the session on Tuesday that also included goalkeeper Sean McDermott and forward Jonathan Walters after they linked up with the squad."