Alex Oxlade-Chamberlain suffered a muscular injury in Arsenal's 2-1 defeat to Manchester City at the Etihad Stadium on Sunday (18 December), Arsene Wenger has confirmed.
Oxlade-Chamberlain was brought off the bench 20 minutes into the second-half, but was replaced by Mohamed Elneny just 13 minutes later. Having taken a first-half lead through Theo Walcott, the Gunners threw away their advantage in a dismal second-half performance, with goals from Leroy Sane and Raheem Sterling securing all three points for Pep Guardiola's side.
Speaking at his post-match press conference, Wenger insisted the change was not a tactical one.
"He is injured. It's a muscular problem, it looks like a hamstring," Wenger said, but did not clarify whether the winger is a doubt for Arsenal's Boxing Day clash with West Brom.
Man City leapfrogged Arsenal in the Premier League table with their win, with the Gunners now just a point ahead of arch-rivals Tottenham Hotspur and four ahead of Manchester United.
After being overpowered by Everton on Tuesday, Wenger's side slumped to their second defeat of the week after wilting dramatically in the second half.
Germany international Sane did appear to be stood offside when he scored his first goal for the club,. Wenger is also unhappy with David Silva's role in City's second.
Wenger told Sky Sports: "I feel we dropped physically in the second half. In the first half we looked always dangerous and sharp.
"And, on top of that, the decisions went against us. The two goals are two offside goals and in a game of that stature, I feel enough is enough for us because we got some bad decisions for the whole season and today I looked at the goals. Both are offside.
"The second one is five yards offside. But what can I do? We have to live with that and look at ourselves and analyse why we lost the game."