Arsenal midfielder Aaron Ramsey is set for a month on the sidelines.
The 23-year-old scored twice before half-time in the Gunners' 4-1 Champions League win over Galatasaray on Tuesday night, but was taken off at the interval after 'tweaking' the problem area.
Double midfield trouble
Initial hopes were that the problem was not serious, but Wenger has been left with a crisis at the heart of his side as Ramsey joins Jack Wilshere on the treatment table at the Emirates Stadium.
The Arsenal chief did not confirm the extent or time-frame of the injury himself during a pre-match press conference this morning (Friday), but the Frenchman confirmed Ramsey is definitely out of the game against Newcastle.
"Ramsey is injured. We got the scan result [on Ramsey] last night. He was getting close to his form of last season," he told reporters.
If the reports are correct, then the Welsh international will also miss the trip to Liverpool a week on Sunday, as well as the capital derby against QPR on Boxing Day. His participation in games against West Ham, Southampton and Hull City in the FA Cup is now also in doubt.
Ramsey has a nightmare record with injuries, dating back to the leg-break he suffered away at Stoke in 2010. However, he'd been fit for the majority of the current campaign and appeared to have found top form in midweek.
Mikel Arteta is also unavailable with a calf problem for the visit of the Magpies, meaning the onus will fall on Mathieu Flamini to anchor the side.
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