Arsenal full-back Kieran Gibbs will be sidelined for between four and five weeks after undergoing a hernia operation.
Gibbs, 22, broke down in training last month and manager Arsene Wenger has confirmed that the left-back will now be out of action until the Christmas.
Wenger will be hoping the England international can return quicker than expected with the Gunners due to play five games in a 15-day period and short on full-backs.
Wenger said: "He has a hernia and had surgery on Thursday. He looks like he will be out for between four and five weeks.
"At first he had an abdominal strain, certainly caused by the fact that he had a hernia already. When the strain was healed we discovered that he had a hernia. We had a fear that could be behind it so we decided to do the surgery.''
Gibbs' absence was not the only defensive blow for Wenger ahead of Saturday's Premier League game at Norwich, with Carl Jenkinson suffering from a back problem.
"We have had some bad news because we have lost two full-backs over the break but apart from that all the players came back in good shape and everybody is available,'' Wenger told the club's official website.
"Carl has a stress fracture in his back. That's just about rest now. We discovered that because he had a pain in his back. First you monitor it, then play a little bit and then you check again because you are cautious.
"We found a small stress fracture that we noticed at an early stage. If he continued to play it could have got worse and then he could be out for a long time. So at the moment the specialist has decided to rest him.''
Wenger added: "[Abou Diaby and Marouane Chamakh] are both back in full training again. Diaby has been out for four or five months so he will need some adaptation. Chamakh is available for the weekend.''
There was more good news for the Gunners with star midfielder Jack Wilshere given the all clear to shed his crutches for the first time since he underwent ankle surgery, although he is not expected to return to action until the new year.
The highly-rated teenager went under the knife two months ago after suffering a stress fracture in his right ankle during the summer.
He has not appeared for the Gunners yet this season, but is set to step up his recovery after he wrote on his Twitter page: "First day without crutches in a while! Feels so good!''