Leinster skipper Johnny Sexton will miss the opening Rainbow Cup fixture against Munster at the RDS on Saturday.
And the clash may just have come too early for a return for a number of Leinster's Ireland internationals.
Scott Penny, the province's top scorer in the PRO14 this season, is available having recovered from a hand injury and Tommy O'Brien is also back after an ankle injury.
However Garry Ringrose, James Ryan, Caelan Doris, Will Connors and Jamison Gibson-Park will all be further assessed this week.
Sexton entered the graduated return to play protocols after the Champions Cup quarter-final win at Exeter and is yet to complete them.
"Johnny is having further assessment and once complete and all information is to hand, a further update will be given," read a Blues statement.
Ryan and Doris have completed their protocols having been stood down from playing due to concussive symptoms - Doris before the Six Nations, and Ryan after suffering a couple of head injuries during it.
Gibson-Park is almost ready to return after a hamstring injury, while Connors is recovering from a knee injury and Ringrose from an ankle injury.
Jack Dunne (ankle), Jimmy O'Brien (hamstring), Rowan Osborne (hand), Adam Byrne (quad), Dan Leavy (knee), Conor O’Brien (knee) and Max Deegan (knee) remain injured and unavailable.
