Robbie Brady is out of the Republic of Ireland's World Cup qualifier in Moldova after it was confirmed he suffered concussion in Thursday night's victory over Georgia.
The 24-year-old midfielder spent the night in hospital after being knocked unconscious in a clash of heads with defender Solomon Kvirkvelia and although he has since been released, medical protocol means he will be able to play no part in Chisinau.
A Football Association of Ireland statement said: "Robbie Brady has been released from the squad following concussion suffered in the 1-0 win over Georgia on Thursday, October 6.
"Brady spent the night in hospital and underwent a precautionary scan, but he has been cleared by the FAI medical staff."
Brady was hurt in a sickening collision during the second half of Ireland's 1-0 win at the Aviva Stadium and was placed in the recovery position by Georgia skipper Guram Kashia.
He regained consciousness under the close attention of medical staff and was carried off on a stretcher wearing on oxygen mask.
However, he was able to talk to teammates in the dressing room before heading to hospital.
His absence represents a significant blow for manager Martin O'Neill, who had already been deprived of the services of several squad members through injury.
Jeff Hendrick will also miss out in Moldova through suspension as a result of his second booking of the campaign against the Georgians, but striker Shane Long is expected to train in Chisinau on Saturday despite limping off towards the end of the game.