Wenger said it would take time for the 21-year-old's injury to heal. "The tackle looked quite bad," he said.
'When you see how it turned his ankle I thought it would be three or four days or it would be four to six weeks. Unfortunately it will be four to six weeks.
"We had some good news about the scan because at some stage we were scared it could be worse. But overall it is a question of patience and rehabilitation.'
There was bad news too for Arsenal team-mate Robin van Persie, who also suffered an ankle injury, against Blackburn Rovers two weeks ago, and is facing a similarly lengthy spell on the sidelines.
Wenger added: "That is bad news,' said Wenger. 'At the start we were optimistic. Maybe a bit too much, thinking it would be one or two weeks. But the damage was bigger than expected and he will be four to six weeks.'
On a positive note Samir Nasri has surprised Arsenal's medical staff by recovering faster than expected after knee surgery and could even be involved this weekend against Bolton.
Johan Djourou and Denilson are back after injury while Sebastien Squillaci could play some part against Bolton after his move from Sevilla. the trio made it through a reserve team run-out in midweek without any problems.