Centre Robbie Henshaw has been ruled for the remainder of Leinster's season with a knee injury.
The 31-year-old Ireland back was replaced in the first half of the team's win over Glasgow nine days ago.
Leo Cullen’s side will also be without prop Tadhg Furlong for Saturday's BKT URC quarter-final against Scarlets at Aviva Stadium (3pm, live on RTÉ).
The Ireland front row "picked up a minor calf injury", said the province, and it's understood that his participation in the upcoming Lions series is not at risk.
Furlong, 32, missed much of the season and four of Ireland’s Six Nations games with a calf / hamstring issue.
He was on the bench for the win over Warriors but didn't feature.
"It just tightened up during the game, so it wasn't worth risking him really," assistant coach Robin McBryde told RTÉ Sport.
"It’s nothing massively serious so we’ll just keep monitoring it and see how he progresses with it."
Asked if he believed Furlong would be available for the latter stages of the URC, if Leinster progress, and the Lions tour, the Welshman said: "Yeah, that’s right."
"Robbie Henshaw has been ruled out of action for the next three to four weeks with a knee injury, which will rule him out of action for the remainder of the Leinster Rugby season," said the club.
Leinster assistant coach Robin McBryde says everyone at the province has "looked at themselves" after their Champions Cup semi-final exit and are keen to re-establish their knockout credentials in Saturday's #URC quarter-final against Scarlets pic.twitter.com/2CP9rPLWXN
— RTÉ Sport (@RTEsport) May 26, 2025
Henhsaw, who played in all three Lions Tests four years ago, remains on a standby list for the tour to Australia.
Meanwhile, wing Jordan Larmour, who last played on 27 December, is stepping up his recovery and a decision about his availability to feature against the Welsh side in Dublin will be made later this week.
There were no further updates on Will Connors, Brian Deeny, James Culhane and Caelan Doris.
Top seeds Leinster host Scarlets, who finished eighth in the table, looking to qualify for a fourth successive semi-final.
As a team who benchmark their success against European titles, McBryde was asked if the semi-final defeat to Northampton Saints, who lost to Bordeaux in the Champions Cup final, was out of their system?
"If we can pick up the [URC] title, it will be a step in the right direction," he said.
"It's one game at a time. We've spoken about it as players and coaches, 'was our mindset right going into that game? Did we think that we had a right to be the final?'
"I don't know but...if we can be good good enough at the weekend, against what is a very cohesive Scarlets team, then we'll end up reaching the same stage as we did in the last three seasons and that gives us the opportunity to go a stage further.
"You can't take anything for granted."
Watch the URC quarter-final, Leinster v Scarlets, on Saturday from 2.30pm on RTÉ2 and RTÉ Player. Follow a live blog on rte.ie/sport and the RTÉ News app and listen to Saturday Sport on RTÉ Radio 1
