West Ham fear Kurt Zouma could miss the rest of the season with the ankle injury he suffered against Brentford on Sunday.
The Hammers have been dealt a severe blow after Zouma was ruled out of tomorrow’s crucial Europa League quarter-final second leg against Lyon. And there are concerns the defender could be sidelined until the summer.
Zouma, who has established himself as a key figure for West Ham since his £30million move from Chelsea last summer, will undergo further tests to learn the full extent of the problem.
But the early prognosis is not good and West Ham fear the French centre-back will be ruled out of their pursuit of European glory.
Losing Zouma for the run-in would present a sizeable headache for David Moyes, who is already without Angelo Ogbonna as he recovers from a serious knee injury.
As well as their shot at the Europa League, West Ham remain in a race for a top-six finish in the Premier League as they bid to establish themselves as a constant European presence.
The injury to Zouma means West Ham face a crunch period in their season with a second-choice defensive pairing of Craig Dawson and Issa Diop.
Dawson has been a constant presence since Ogbonna's injury in November and excelled against Lyon during the first leg last week.
But question marks remain over Diop, who was at fault for Brentford's opener on Sunday having come on to replace Zouma in the 2-0 defeat.
West Ham are also without left-back Aaron Cresswell in Lyon following his controversial red card in the first leg at the London Stadium, which ended 1-1.
Ben Johnson is expected to deputise at left-back in the second leg following Vladimir Coufal's return from hernia surgery, though Moyes has considered dropping Declan Rice into defence when he has been short this season.
In a statement on Tuesday, West Ham said: "Kurt Zouma will miss Thursday's UEFA Europa League quarter-final second leg tie against Olympique Lyonnais.
"The France international defender is to remain in London for further tests and examination on the ankle injury he suffered during Sunday's Premier League match at Brentford.
"Everyone at West Ham would like to wish Kurt a speedy recovery."
West Ham went five games without a win in all competitions following the loss of Zouma to a hamstring injury in December.
Moyes wanted to signed a central defender in January but a move for Marseille's Duje Caleta-Car was unsuccessful and a centre-half remains a priority this summer, with Lille's Sven Botman having been tracked.
West Ham face Burnley in the Premier League on Sunday as they look to bounce back from last weekend's defeat at Brentford.
