Gabriel Jesus is out of Arsenal's season start due to surgery.
The Brazil striker has had a clean up operation on his knee.
Gunners manager Mikel Arteta, speaking after their preseason friendly against AS Monaco, said: "It's a big blow because we had him back to his best.
"Unfortunately he had a little procedure this morning. He had some irritation in the knee and we had to get it resolved. It's not major but he will be out for a few weeks I think.
"We had to make a decision and the best one is to protect the player and to get him back as quickly as possible, so we decided to do it."
