FIFA has confirmed to Sky Sports News it is investigating whether Robbie Brady threw a headbutt at Wales defender Ashley Williams.
The incident took place in the 61st minute of the Republic of Ireland's 1-0 win in Cardiff and was missed by referee Damir Skomina.
A FIFA spokesperson said they are in the process of collating evidence to see whether Brady should be charged.
If he is, the Burnley midfielder could miss at least the first leg of their World Cup play-off next month.