Johnny Sexton will step up his comeback from injury this week as he nears a return to action.
The Leinster and Ireland fly-half is recovering well from the medial ligament tear in his right knee sustained in the Heineken Champions Cup win in Northampton last month.
He will take a more active part in training this week but will not be available for the European game with Lyon on Sunday in the RDS.
It is hoped he will be fit in time for the start of the Six Nations.
Leinster senior coach Stuart Lancaster says that Sexton is making good progress, although a return to action is still a number of weeks away.
"He's making good progress. But it's not an injury that you suddenly go from being injured to being fit again in two or three weeks," he said.
"It takes time to strengthen the ligament, to start running again and to go with everything that goes from being injured to back playing a robust game like rugby.
"So it's going to take some time but he's made great progress. But he's not going to be available this weekend."
Lancaster also added that it's "unlikely" the Ireland international will be available for Leinster's Heineken Champions Cup fixture against Benetton Treviso on 18 January.
Meanwhile the province are awaiting further news on the calf injury picked up by James Ryan in the routine win over Connacht in the Pro14 last Saturday.
Ryan was substituted in the first half and will be monitored this week to assess his prognosis and if he is fit to play the French side.
Joe Tomane came through the game unscathed after a hamstring injury.
Michael Bent (calf), Rory O'Loughlin (shoulder), Ronan Kelleher (hand), Vakh Abdaladze (back), Jack Conan (foot), Barry Daly and Dan Leavy (both knee) remain out.
