Arsene Wenger has ruled Laurent Koscielny out of Arsenal's next four games as the club continue to investigate the defender's achilles problem.
The France international was added to the Gunners' lengthy injury list when he returned from international duty ahead of schedule with the French FA later claiming the defender has been suffering with a problem in both his achilles tendons for a number of months.
Wenger last week denied claims Koscielny would need surgery to address the problem but was unable to give a conclusive update on his centre half's condition.
"I cannot give you any date," Wenger told reporters when asked of the defender's return date. "I hope he will be available after the international break."
According to his manager's prognosis, Koscielny will miss Saturday's game against Sunderland, the visits of Burnley and Anderlecht and the trip to Swansea City on 9 November. Arsenal's first game back after the next international break is against Manchester United on 22 November.
After being beset by injury woes in recent weeks, Wenger was relieved to see his side come through unscathed in their 2-1 win over Anderlecht in Wednesday's Champions League group stage clash.
The Gunners boss has also welcomed back long-term absentees Theo Walcott and Serge Gnabry to his squad but will hold off on handing the England international a return to the first team against Sunderland on Saturday.
Walcott, who has not played since January when he suffered the cruciate ligament injury that ended his season, played for the club's under-21 side last Friday following his return to training but Wenger is wary of throwing him straight back into he first team.
"He has to get used to contact again," Wenger continued. "It takes time to get used to being kicked again."
Jack Wilshere is Wenger's only new absentee ahead of his side's visit to the Stadium of Light with the midfielder set to serve a suspension.