Ireland are awaiting a fitness update on centre Garry Ringrose after he limped out of Leinster's big Pro14 win over Ulster at the weekend.
The 22-year-old sustained an ankle injury which could rule him out of the first two Six Nations games against France and Italy.
Ringrose had recently returned after shoulder surgery in the summer.
Leinster have confirmed he will miss the final European Champions Cup pool games against Glasgow and Montpelier.
Ringrose, who has 11 caps, missed Ireland's three autumn internationals as he was still recovering from the operation he had in July.
If he cannot be included in Joe Schmidt's squad for the 3 February fixture away to France, Bundee Aki of Connacht could partner Leinster's Robbie Henshaw in midfield.
Ireland's second match sees them host Italy in Dublin on 10 February.