LEINSTER welcome back out-half Jonathan Sexton and backrow Shane Jennings to face Brive in their Heineken Cup match on Saturday.
Jennings, who served a 12-week ban for making contact with the eye area of London Irish secondrower Nick Kennedy, could be in line for a start even though he hasn't had any match for the Blues since October.
"We have a lot of difficult decisions to make in regard to selection," said coach Michael Cheika. "Shane is obviously a quality campaigner and he's important to our team.
"Sean O'Brien has done an unbelievably good job. Now we have to look at the options of playing them together, playing them separately, giving them game time, or letting them battle it out for the peak games, so it is difficult.
"It's difficult because you have to leave one out of the starting line-up at this stage. I don't think we'd play the two of them together at this point, so that's where it becomes difficult.
"I definitely would have preferred to have both Shane and Jonny Sexton to have had some game time under their belts, no doubt about it, for Jennings even more than Sexton.
Sexton suffered a double fracture in his hand during Ireland's 15-10 win over South Africa in November.
"I felt after four weeks maybe I could have played and I was dying to play, but the doctors had said there's no point. If you get a bang, you might need an operation, so it was best just to leave it, and I'm delighted I did now in hindsight because it's 100pc right," said the 24-year-old Sexton.
Cheika, meanwhile, is in no doubt about the challenge facing his team.
"The (Brive) team that we're playing now is very different to the Brive side we played in October. In their last four games they have beaten Toulouse and Perpignan at home and defeated Albi away in the snow. They're very combative and their backs are giving them a good platform.
"Depending on the conditions, I think that we're going to be in for a real torrid battle on the ground. They have accumulated a lot of points in their own championship now and that's a consequence of improved play.
Meanwhile, Leinster have requested the use of Croke Park should the RDS be deemed unplayable.
The call was made before the recent freezing temperatures began to thaw out in line with ERC rules.