The midfielder limped out of the win over Crystal Palace after just eight minutes, and will now miss clashes against Liverpool, Chelsea and Borussia Dortmund with a groin injury.
The midfielder is set to miss the club's top-of-the-table Premier League clash against Liverpool next Saturday, as well as the crucial Champions League trip to Borussia Dortmund and Tuesday's Capital One Cup tie against Chelsea.
Flamini was substituted in the eighth minute of Arsenal's 2-0 win at Crystal Palace on Saturday with what Arsene Wenger confirmed afterwards was a groin problem that would be assessed by medical staff.
Goal understands that Flamini is now expected to be sidelined for a fortnight with the injury and that he is targeting the trip to Manchester United on Nov. 10 for his return.
The Frenchman's absence is a blow to Arsenal as the club prepares for a glut of key fixtures that could determine whether it is capable of mounting a genuine title challenge, as well as ending an eight-year trophy drought.
Flamini has been a revelation in central midfield since returning to the club on a free transfer in the summer.
He had returned to the Arsenal side against Palace after missing the defeat to Borussia Dortmund last Tuesday with a minor head injury sustained against Norwich City the previous weekend.
Teenager Serge Gnabry, who won the penalty for Arsenal's opening goal at Palace after replacing Flamini, also collected an ankle knock at Selhurst Park but it is not considered serious and he is expected to be in contention for Tuesday's match against Chelsea.
Wenger will ring the changes for the London derby, despite the caliber of the opposition, although he is expected to name first-team regulars on the bench.