Arsenal defender Thomas Vermaelen has played a successful return to their Carling Cup victory over Bolton Wanderers.
The Belgian international has been with a hamstring injury, but started at the Emirates Stadium, played 84 minutes, before it with a "tight calf."
"He's very good, but he had to come off a calf problem," said Wenger.
"I hope it's not so bad.
"He is a bit short for Saturday. I do not know what happened.
"We got him to the test tomorrow, but it did not look so bad.
"He has been for a long time and had only one training session yesterday with the team.
"I did not expect a game, the intensity, because it's a really tough game for a central defender was tonight, as they put us under pressure in the second half."
He added: "I do not think that it's a calf strain, I think it is only a narrow calf, because he not played 90 minutes for three months.
"He wanted to dissolve. In fairness, I did not want to undress him, because I was stupid to go now with four minutes if we thought a goal.
"He was firmly convinced them he could not walk, so I hope it is not so bad."