Arsenal will not be able to call upon the services of Olivier Giroud for their remaining Champions League group matches, as the striker was not included in their original squad list.
The Frenchman injured his ankle in a draw against Everton on August 23 and was not expected to return until January.
Due to the group stage finishing in December, he was left out of the Gunners' 25 man 'A List' for the tournament.
However, he has recovered quicker than expected and scored on his comeback during his club's 2-1 defeat against Manchester United at the weekend.
Arsenal will take on Borussia Dortmund at the Emirates on Wednesday, before finishing their group stage campaign in Turkey against Galatasaray on December 9.