The Germany international was substituted at half-time during Arsenal's Champions League draw with Bayern Munich on Tuesday evening with a hamstring problem
Ozil was substituted at half-time during the Gunners' Champions League draw with Bayern Munich on Tuesday, with his anonymous performance widely criticised within the media.
But it soon emerged that the Germany international had sustained a hamstring injury in the early stages of the match, and Wenger admits he will be missing for some time.
"When the minimum is three, the maximum is six so let's say four weeks," the Gunners boss told reporters.
"It's a blow to lose Ozil but I'm confident we have the quality to deal without him. We have many good players in our squad."
On Kim Kallstrom, who has not featured since arriving at the Emirates Stadium on the final day of the January transfer window, Wenger added: "Kallstrom is back in the squad and will be available for Sunday."