Vermaelen out for up to three weeks
The 24-year-old, who has scored seven league goals and missed just one game this season, lasted only 19 minutes of the 2-1 defeat and will sit out Sunday's trip to Wigan Athletic and the home match against Manchester City.
"Certainly it is a calf strain. [He will be out for] two to three weeks," manager Arsene Wenger said on the club's website on Thursday.
Arsenal, third in the standings and six points behind leaders Chelsea, have recently suffered several injuries to key players including captain Cesc Fabregas, defender William Gallas and forward Andrei Arshavin.
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