Mesut Ozil is one of six first-team players to return to full training ahead of Arsenal's trip to West Ham in the Premier League on Saturday.
Ozil has not featured for the Gunners since their 1-1 draw with Brighton and Hove Albion on Boxing Day, the Germany international subbed at half-time with a knee injury.
After missing Arsenal's last three matches, Ozil is back in contention to face the Hammers after taking part in Unai Emery's preparations on Wednesday.
His return is a welcome boost for Emery, who has seen his squad – particularly the defence – plagued by injuries in recent weeks, problems that appear to be easing.
Full-backs Hector Bellerin (calf) and Nacho Monreal (hamstring) are back in contention, while central defenders Dinos Mavropanos (groin) and Shkodran Mustafi (hamstring) have also returned.
Laurent Koscielny – who suffered a back spasm during the warm-up ahead of Saturday's FA Cup third-round victory over Blackpool – also took part in training to give Emery a plethora of options to choose from.
Meanwhile, Armenia international Henrikh Mkhitaryan is expected to be back in February after a foot injury.
The Gunners are facing back-to-back London derbies, as they will take on Chelsea the weekend after their match against West Ham.
Arsenal sit in fifth position in the Premier League, three points behind fourth-place Chelsea.