Arsenal manager Mikel Arteta provided an update on absences ahead of their Champions League game in midweek.
The Gunners are set to take on RC Lens in the group stages on Wednesday night.
Fabio Vieira, who was suspended in the Premier League over the weekend, has undergone an operation on a groin issue.
"He's been having some discomfort and we tried to have alternative treatment with him, and he wasn't improving so we've sent him to see a specialist and that was to get an operation done in his groin, and we did that yesterday," Arteta told reporters.
"We're expecting him to be out for weeks now.
We don't expect him to do that [be back this side of the break], so let's see how he evolves and obviously, the operation was done yesterday so we're going to have to wait and see, but we will take it as it comes."