Arsenal forward Gervinho has been ruled out for three weeks with an ankle injury, manager Arsene Wenger has confirmed.
The injury - sustained during last weekend's 1-0 win over Queens Park Rangers just 11 minutes after coming on as a substitute - means the Ivorian is expected to miss as many as five games for the Gunners, including several key fixtures.
Arsenal travel to Old Trafford to face Manchester United on Saturday before visiting German side Schalke in the Champions League next Tuesday.
Two consecutive London derbies at Emirates Stadium, against Fulham and Tottenham Hotspur, then follow before a potentially decisive European fixture against French champions Montpellier.
Gervinho, who has featured as a central striker this term having spent his first season with the club as a winger, has netted three times in the Premier League from seven starts in 2012-13.
His absence is likely to lead Wenger to ask Olivier Giroud to spearhead the attack at Old Trafford on Saturday, following on from his game-changing introduction as a substitute in the 7-5 triumph at Reading on Tuesday - although Marouane Chamakh, who netted twice at the Madejski, will also be in the running, as will Lukas Podolski.
Meanwhile, Wenger has confirmed that Kieran Gibbs, Wojciech Szczesny and Abou Diaby all have no chance of facing Sir Alex Ferguson's side.