Bukayo Saka was substituted with an injury during Arsenal's 2-1 defeat by Lens in Tuesday night's Champions League clash.
He was taken from the field in the 34th minute of the match and is the second time in two matches that he's suffered a knock.
It didn't look good for the English winger either, who was seen wincing in pain as the physio team arrived onto the pitch to treat him.
He left the field early during Arsenal's 4-0 win against Bournemouth on Saturday, but had returned to training on Monday in what was a huge boost to Mikel Arteta's side, with a monumental clash against Manchester City coming up at the Emirates Stadium on Sunday.