Racing 92 will be without captain Dimitri Szarzewski for Sunday's European Champions Cup semi-final with Leicester Tigers due to a knee injury.
The hooker suffered the injury during Racing's quarter-final victory over Toulon 10 days ago and will miss his side's first appearance at this stage of the competition as a result.
Szarzewski's absence in the front row is a huge blow to the Top 14 side, and denies him one of the biggest games of his 14-year European career.
He is not the only absentee ahead of Racing's trip to the City Ground, with flanker Yannick Nyanga also on the sidelines having been ruled out for six weeks with an ankle ligament problem.
There was some good news for the French outfit, though, as centre Casey Laulala returned to training on Wednesday and was declared fully fit to feature.