The Gunners midfielder is likely to be unavailable before Christmas, however the club insist the Switzerland international will not need surgery
Arsenal have suffered a major injury blow following the news captain Granit Xhaka has been ruled out with a knee problem.
Xhaka has been a key man under Mikel Arteta, with the Gunners beginning to turn their early season form around including a 3-1 victory over north London rivals Tottenham in the Premier League.
However the midfielder is now set to be out until Christmas, although Arsenal say he will not require surgery.
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