Leinster starlet Joey Carbery will find out if he requires surgery after a scan on an ankle injury.
The out-half limped out of Leinster's Champions Cup win over Northampton on Friday night.
With first choice Jonathan Sexton and Cathal Marsh already out injured, it will test the strength in depth at No 10 for the province.
In the short-term Ross Byrne (21), Carbery's replacement on Friday, will start Saturday's return fixture with the Saints.
Auckland-born Carbery has earned rave reviews as the 20-year-old makes an impact at senior level.
Off The Ball's premier rugby correspondent and former Ireland captain Brian O'Driscoll picked out his best attributes in October.
Leinster’s Ross Byrne against Northampton ©INPHO/Billy Stickland
"He looks like he has loads of confidence. He has the feet of a back three player and his default isn't to go and break himself. He sees his options but more often than not when he goes and has a break himself, he makes a half-yard at least or makes a half-break. I think that's the sign of a really good player. He doesn't over-play it himself," said O'Driscoll.
Carbery has since gone on to make his senior debut for Ireland, featuring as a substitute in the famous win over New Zealand in Chicago in November and returning for the Australia game.
Byrne's appearance to replace Carbery against Northampton was his fifth cap of the season for the Leinster senior team.
He has been capped 15 times for Ireland's under-20s.
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