The Leinster and Lions star was originally named on the bench
Leinster have suffered a late blow ahead of their PRO12 semi-final against Scarlets, with the news that Sean O'Brien has been pulled out of the squad.
O'Brien had been due to start the game on the bench, but head coach Leo Cullen confirmed that Carlow native is suffering from a tightness in his calf and a decision has been taken not to risk the injury further.
The news will be concerning to both Leinster and the Lions, and puts a doubt into his participation in next week's PRO12 Final, should Leinster overcome their Welsh opponents on Friday night. O'Brien was also selected for his second Lions tour last month.
As a result of his withdrawal, Ross Byrne comes onto the bench in his place and there will be a numerical shuffle in the replacements as a result with Jamison Gibson-Park now wearing number 21 instead of O'Brien and Byrne wearing the number 22 jersey.
Otherwise the team that was announced on Thursday afternoon remains the same.
Leinster team and replacements to face Scarlets:
(15-9): Joey Carbery, Adam Byrne, Garry Ringrose, Robbie Henshaw, Isa Nacewa (capt), Johnny Sexton, Luke McGrath.
(1-8): Jack McGrath, James Tracy, Tadhg Furlong, Ross Molony, Hayden Triggs, Rhys Ruddock, Josh van der Flier, Jack Conan.
Replacements (16-23): Richardt Strauss, Cian Healy, Michael Bent, Devin Toner, Dan Leavy, Jamison Gibson-Park, Ross Byrne, Zane Kirchner.