Adam Byrne will play no part in Leinster's final push for their double-double bid.
The Blues winger picked up a quad injury against Glasgow Warriors the weekend before last and has been ruled out for the remainder of the season, thus joining Dan Leavy and Josh van der Flier on the sidelines.
Sean Cronin, who came off with a calf injury in the 33rd minute of the province's Champions Cup semi-final win over Toulouse on Sunday, will be further assessed this week.
But the hooker will play no part in Leinster's final regular season game against Ulster on Saturday at the Kingspan Stadium (5.15pm kick-off).
Rhys Ruddock felt unwell after the captain's run on Saturday and was withdrawn, with his place taken against Toulouse by Scott Fardy.
The back row has re-entered the graduated return to play protocols. Jamison Gibson-Park could return this week, having sustained a hamstring injury against Glasgow and missed the big European tie.
Meanwhile Andrew Porter had a minor pectoral muscle injury last week and will also be assessed this week before a decision is made on his availability.
Ross Molony could also feature in the coming weeks after a back injury.
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