Arsenal are already without Robin van Persie, Theo Walcott, Thomas Vermaelen and Lukasz Fabianski for the game at the Camp Nou, while Alex Song is considered doubtful and Cesc Fabregas is still not certain to play.
Wilshere, Arsenal's stand-out player at the Emirates in his side's 2-1 victory, could also now miss out after he was caught by two Sulley Muntari tackles in Saturday's 0-0 draw against Sunderland.
"Wilshere has an ankle problem and we'll wait until Monday or Tuesday to see if he's back," Wenger said. "We will see how he responds to treatment."
Wilshere, who was due to miss Sunday's training session, made no mention of the injury in his post-match interview as he stressed his belief that Arsenal could prevail against Barca.
"We know we've got the confidence going to Barcelona," he told BBC Sport. "We beat them here; we can beat them there."
Wenger has stressed that Arsenal must put in a strong defensive performance at Barca if they are to progress, but indicated that he has no plans to park the bus.
"It will be very important for us to defend well because when you go to the most effective attacking team in the world, you want to have your best defenders available," he said. "We will look to defend well and attack well. We are not a team that will refuse to attack - we know that.
"The challenge will be to find the right balance between having a team who can defend, as well as one that has a good opportunity, every time it has the ball, to go forward."