The Republic of Ireland's Robbie Brady will miss Sunday's World Cup qualifier in Moldova after being knocked out in Thursday's 1-0 win over Georgia.
The Norwich player's neck was put in a brace and he was given oxygen as he was carried off on a stretcher late on.
Brady spent Thursday night in a Dublin hospital and the Football Association of Ireland said his concussion had led to him being released from the squad.
Manager Martin O'Neill said that Brady was "out cold" after a clash of heads.
"He was concussed," added the Republic manager.
"He's come back around and the doctors are quite pleased with him."
Brady's absence from O'Neill's much-depleted squad comes after midfielder Jeff Hendrick's booking in Thursday's fortunate 1-0 win resulted in his suspension for Sunday's game.
Daryl Murphy, who scored the Republic's late equaliser in last month's 2-2 draw in Serbia, was among eight players already ruled out of this week's qualifiers with Keiren Westwood, Harry Arter, Stephen Quinn, Kevin Doyle, Aiden McGeady, Anthony Pilkington and Marc Wilson also absent.
But striker Shane Long is expected to be fit for the game in Chisinau despite limping off late in Thursday's game with a leg muscle injury.
Seamus Coleman's first international goal in the 56th minute secured the Republic's win after Georgia had twice hit the woodwork in a dominant first half at the Aviva Stadium.