Daniel Farke has confirmed the knee injury sustained by Ilia Gruev this week has ruled him out of Sunday's FA Cup semifinal against Chelsea and for the rest of the season.
Bulgaria midfielder Gruev sustained the injury in training and missed Wednesday night's 2-2 draw at Bournemouth.
"Sadly bad news with Ilia Gruev. A meniscus injury is confirmed and will keep him out for the whole season and he won't be able to help us for the FA Cup or the run-in." Farke said.
"We expect to have him back for the start of pre-season. It's not ideal for us and we all feel for him."
Farke said he was hopeful Jayden Bogle would recover in time from the foot injury that forced him off during half-time at the Vitality Stadium and that fellow defender Sebastiaan Bournauw should also shake off an ankle injury.
"Jayden Bogle got a hit against his foot, it seems to be not too bad," Farke said. "We need to wait and see how quickly he can recover, we hope to have him available.
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"During the warm-up [Sebastiaan Bornauw] rolled his ankle, [on Wednesday] it was pretty sore and also he was not able to join us in team training, I hope it's not too bad and hope to have him back in team training [on Friday] and if so, he will be available."
Farke also remains hopeful that midfielder Anton Stach will be included in his plans for Leeds' first FA Cup semifinal since 1987.
Germany international Stach damaged ankle ligaments in the quarterfinal penalty shootout win at West Ham and has missed Leeds' last three league matches.
"He's not yet in team training, but we have a few more days and we will see. Of course if a key player like him is back in training then he has a chance. Let's see in the next 72 hours," Farke added.
Sean Longstaff's stoppage-time equaliser at Bournemouth lifted Leeds nine points clear of the Premier League relegation zone before Sunday's Wembley clash with Chelsea, when they will bid to reach their first FA Cup final since 1973.