Arsenal have provided a fresh update on Bukayo Saka ahead of the Premier League game at West Ham United on Sunday.
Saka sustained a minor hamstring injury against Tottenham Hotspur last weekend and he subsequently missed the Olympiacos tie.
He has returned to training since and the Gunners have confirmed that he is available for selection against the Hammers.
However, Willian is considered doubtful for the London derby after missing the midweek European game with a calf problem.
The Brazilian was involved in training on Saturday. A late fitness test may determine his inclusion in the matchday squad.
Arsenal are currently 10 points behind the top four, but they can reduce the deficit with the game in hand against the Hammers.
They have a good league record against their London counterparts and have beaten them in five of the last six meetings.