Arsenal manager Arsene Wenger has said midfielder Francis Coquelin is facing three months on the sidelines.
Coquelin, 24, suffered a knee injury in Arsenal's 2-1 loss at West Brom on Saturday, and Wenger said on Monday he was facing at least two months out.
Coquelin has emerged as a key player for the Gunners since being recalled from his loan at Charlton in December 2014.
Arsenal manager Arsene Wenger hailed the performance of Mesut Ozil as the Gunners beat Dinamo Zagreb 3-0 in the Champions League on Tuesday night.
Ozil was on the scoresheet, as was Alexis Sanchez with two, to keep Arsenal's hopes of reaching the knockout stage alive.
Bayern Munich's 4-0 win over Olympiakos means the Gunners must win by two goals or a one-goal victory margin of 4-3 or higher when they travel to Greece on Dec. 9.
Wenger is quoted by the BBC as telling BT Sport: "It promises to be...
Arsenal kept their Champions League hopes alive with a routine victory over Dinamo Zagreb.
Arsene Wenger's men had lost three of their opening four Group F fixtures, including defeat in Zagreb, and looked to be on the verge of failing to make the knock-out stages of the competition for the first time in 16 seasons.
But, knowing they needed Bayern Munich to beat Olympiacos in Germany as well as take care of their own match, the Gunners held up their end of the bargain as Mesut Ozil opened the scoring...