Brentford defender Ben Mee has been ruled out of the remainder of the season with an ankle injury.
The 34-year-old was assessed by the club's medical staff this week and manager Thomas Frank said his worst fears over the injury were confirmed.
"He got a fracture to his ankle in the contact at West Ham. That is our entire back four out," Frank said.
"We have a good squad, we have good players, but that makes it a little bit more tough."
Brentford are already without a number of key players which has left Frank with a depleted squad for Saturday's visit of Chelsea.
Defenders Rico Henry, Aaron Hickey and Ethan Pinnock are all out injured along with midfielder Joshua Dasilva plus forwards Kevin Schade and Bryan Mbeumo
Frank added: "I've got potentially seven starters out. That's life and it's up to me and the players to find a way out.
"We were in a 12-game unbeaten run and everyone thought 'wow, Brentford are so good.' It's still the same staff, owner and players.
"Why is it now that we lost 10 of the last 12? Sometimes not good performances, sometimes things go against us and also injuries.
"I'm very optimistic. I'm a massive fighter and my players are massive fighters. When things are going against you, there's only one thing to do and that's pull together."
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