Arsene Wenger has confirmed that Arsenal midfielder Jack Wilshere faces extra time on the sidelines with ankle inflammation.
As reported by the Daily Mail, Wenger told reporters in his pre-match press conference that Wilshere will undergo extra treatment on the ankle complaint after recent swelling.
The Arsenal boss also revealed that Alex Oxlade-Chamberlain faces three to four weeks out with the hamstring injury suffered against Manchester United earlier this week.
When asked how long it would be before Wilshere returned, Wenger said: "I don't know because we have to respect the progression of his training and it's very difficult to give you a day-to-day.
He was asked whether it was a matter of weeks regarding Wilshere's return. Wenger said: "Yes. He had a little inflammation in his ankle so we decided to do it [the operation].
"We had to rest him anyway."
Champions League hopes
The Gunners welcome West Ham to the Emirates Stadium on Saturday afternoon as they push towards Champions League qualification.
He had a little inflammation in his ankle - Wenger on Wilshere
Currently sitting in third place, a positive result against the Hammers will put pressure on rivals Manchester United, Southampton and Tottenham, all of whom play on Sunday, while Liverpool play Swansea at the Liberty Stadium on Monday night.
Monaco next Tuesday
Wenger will also have one eye on Arsenal's Champions League second leg match against Monaco in France next week.
They trail 3-1 on aggregate after a disastrous first leg game at home, and travel to Monaco more in hope than expectation. Having said that, they will be full of confidence after progressing past United in the FA Cup thanks to a 2-1 win at Old Trafford on Monday this week.
The only negative from that match was the injury to Chamberlain, with the midfielder joining Wilshere on Roy Hodgson's England absentee list for the upcoming matches against Lithuania and Italy.