Johnny Sexton and Tadhg Furlong are in a race to be fit in time for Leinster's Heineken Champions Cup opener against Racing 92 on Saturday.
Sexton had been targeting a return for the trip to France, however, the Leinster and Ireland captain is still struggling with the calf issue that ruled him out of international duty last month, and as such, he has not yet returned to training.
Ross Byrne is primed to continue at out-half, should Sexton miss out, as looks increasingly likely to be the case.
Meanwhile, having come off the bench in the second-half of last weekend's comeback win over Ulster, Furlong was forced off during the latter stages at the RDS.
Furlong suffered an ankle injury, and like Sexton, the tighthead may be forced to sit out the trip to Le Havre.
In more positive news, Charlie Ngatai is expected to train fully this week after his recovery from a shoulder injury picked up during the recent victory against Glasgow.
Jamie Osborne provided inside centre cover for the Connacht win, but Ngatai's experience against a powerful Racing outfit could be called upon.
James Lowe came through the game at the weekend against Ulster with no issues after his return from a troublesome calf.
Robbie Henshaw (wrist), Martin Moloney (knee), Ciarán Frawley (knee), Will Connors (bicep), James Tracy (neck), Charlie Ryan (knee) and Tommy O’Brien (knee) remain sidelined.
