Arsenal midfielder Mathieu Flamini looks set to miss Tuesday's Champions League clash with Borussia Dortmund, after suffering from concussion in Saturday's 4-1 Premier League victory over Norwich.
The Frenchman picked up the head injury in the first half, and was forced off after suffering from double vision, meaning he is now a major doubt for the visit of last season's European finalists.
Manager Arsene Wenger will wait to hear how serious the problem is before naming his squad, but expects to be without his holding midfielder.
"He had concussion," said Wenger. "He had double vision, so on the advice of the doctor I took him off because I did not want to take any gamble.
"I don't know if he'll be available for Dortmund, it depends now what the doctors will decide.
"Sometimes they are not allowed to play for five days, it depends how big the concussion was," he added.
Flamini has been in impressive form so far this season after rejoining the club this summer on a free transfer from AC Milan, and has been a key part of Arsenal's early season success.
A superb display against Norwich saw the Gunners retain their position at the top of the Premier League after eight games, and attention now turns to European competition where they have been equally impressive.
Wins over Marseille and Napoli mean they top the group with 6 points heading into Tuesday's mouthwatering fixture.
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