Arsenal midfielder Lucas Torreira will miss most of the rest of the season after fracturing his ankle.
The Uruguay international was injured in the 2-0 FA Cup win at Portsmouth last Monday and left the stadium on crutches, wearing a protective boot.
Scans have confirmed he has sustained a fracture that will take between eight and 10 weeks to heal, meaning he could sit out the remainder of the Gunners' Premier League and FA Cup campaigns.
The news is a blow to Arsenal, which gave its hopes of Champions League qualification a boost with a 1-0 league win over West Ham on Saturday.
It heads to Manchester City on Wednesday with a string of injury concerns, with Calum Chambers (knee), Sead Kolasinac (shoulder) and Cedric Soares (knee) all out, while Shkodran Mustafi (thigh) faces a late fitness test.
The win over the Hammers means Mikel Arteta's side is eight points behind fourth-place Chelsea, with a game in hand, and five adrift of Manchester United in fifth.
A top-five finish could be enough to secure Champions League football if City's ban from European competition is upheld by the Court of Arbitration for Sport.
Following a shock Europa League last-32 exit at the hands of Olympiacos, only a strong finish to the league season will see the Gunners return to Europe's top competition next season, while the FA Cup represents their only hope of silverware.
It takes on Sheffield United at Bramall Lane in the quarterfinals on the weekend of March 21.
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