Arsenal are not yet sure of the Severity of the injury sustained by Olivier Giroud against Everton, manager Arsene Wenger has revealed.

Wenger confirmed at a pre-match press conference this afternoon that the French striker will have to sit out tomorrow's Champions League playoff second leg against Besiktas.

Reports have emerged that the 27-year-old, who picked up the knock late on at Goodison Park on Saturday, could have broken a bone in his foot and be out of action for as long as three months.

However, Wenger insisted that the full extent of the damage is not yet known and that he will see a specialist tomorrow.

"It can be [a long term injury]," he said. "We'll see tomorrow. I don't know [if it's broken]. It's sad for us."

Arsenal were held to a goalless draw in last week's first leg against Besiktas in Turkey. Victory tomorrow will guarantee their place in the group stage for the 17th straight season.