Arsenal could be without centre-back Laurent Koscielny for Tuesday's Champions League clash with Paris Saint-Germain due to an eye injury.
Koscielny was caught in the face by an opponent's studs during Saturday's 2-1 victory over Southampton, resulting in swelling around the eye area.
"It is a little concern," Wenger said after the game. "It's already very swollen."
Should the 31-year-old fail to recover in time, Wenger would most likely field summer signings Shkodran Mustafi and Rob Holding in the centre of defence, with club captain Per Mertesacker and Gabriel Paulista both unavailable through long-term injury.
Koscielny's absence would be a significant blow to Wenger, with the France international currently serving as captain.
"He is one of the most experienced players we have now here," Wenger said. "He is one of the longest-serving defenders and I think he is one of our best players.
"When I think about the squad, when you choose a captain as well, you think of one with a good chance to play in every single game and that's not easy nowadays. He has committed to the club for a long contract and he has always improved every year. Today he is an outstanding centre-back."
Koscielny scored an overhead kick for the equaliser against Saints, and Wenger added: "He doesn't score that when it is 4-0 for you, he scores at 1-0 down and that's always a special quality. It was his birthday and he gave himself a great present."