Ireland called Paddy Wallace into their squad Friday as injury cover for fly-half Jonathan Sexton just a day before Saturday's Six Nations international against France in Paris.
Starting stand-off Sexton suffered what an Ireland team spokesman said was a "tweak" in his thigh muscle during Friday's kicking session.
After Sexton was examined by Ireland's medical staff, officials decided to send for Wallace, who had been due to play for Ulster in a Celtic League match against Newport Gwent Dragons on Friday.
The Ireland spokesman said Sexton "had not been ruled out" of the France match and that the medical team would monitor him over the next 24 hours before a decision was made on the matchday 22.
Sexton will have longer to recover than might normally be the case as Saturday's match at the Stade de France does not kick-off until 9pm local time (2000GMT).
If Sexton is ruled unfit, veteran outside-half Ronan O'Gara will start with Wallace on the bench.
Ireland lost 23-21 to Wales in Dublin in their tournament opener last weekend while France beat Italy 30-12.