The Real Madrid star watched from the stands as Wales were thumped 4-1 by Spain in Cardiff on Thursday, with manager Ryan Giggs admitting after the game that it was looking unlikely that Bale would be available for the clash.
"It's unlikely at this point," Giggs told 'Sky Sports'.
"It's nothing serious but the closer we get to the game, we will have to make a decision."
It is thought that Bale must train on Sunday to have any chance of featuring against the Irish, with Giggs reluctant to take risks with hi star man's fitness, partciualrly with Real Madrid keepign a close eye on the situation.
The Spanish giants are already thought to be unhappy Bale opted to go away on international duty, and would rather he had stayed back for treatment as they prepare for three games in eight days following the international break, including 'El Clásico'.
Wales already appear to have put a contingency plan in place should Bale not make it, calling up Ipswich winger Gwion Edwards on Friday.