The England midfielder picked up the knock during the 3-1 defeat to Aston Villa on the weekend and Goal understands he will now be out until mid-to-late November
By Wayne Veysey | Chief correspondent
Arsenal midfielder Alex Oxlade-Chamberlain has been ruled out for three months with medial knee ligament damage, Goal can reveal.
The club's medical team have received the results of the scan the England international had on his injured left knee on Monday.
Goal understands it showed that Oxlade-Chamberlain has strained his medial ligaments and the doctors expect he will be out until mid-to-late November.
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Oxlade-Chamberlain was carried off at Emirates Stadium last Saturday following a collision with Aston Villa's Antonio Luna during the 3-1 defeat.
Wenger admitted afterwards that it looked to be a "bad injury" but the extent of the damage could not be fully assessed until the swelling on the midfielder's knee had diminished.
It is a shattering blow for Oxlade-Chamberlain, who had got the nod over Lukas Podolski to start for Arsenal last weekend and had been earmarked for more playing time this season, his third at the club.
It is also a setback for England manager Roy Hodgson, who would have been expected to select the 20-year-old for the crucial World Cup qualifiers in September and October.
Oxlade-Chamberlain confirmed the extent of his injury on Twitter, but hopes to be back in action before the turn of the year.
"Gutted i'm injured so early in the season. But I'm going to be working hard to hopefully be back playing in 3 months.Thanks 4 all ur support [sic]," he tweeted.
Wenger has been forced to step up his efforts in the transfer market following the injuries to Arteta and Oxlade-Chamberlain, and on the back of a summer in which he has failed to make a single senior signing.
Arsenal had a £10m bid rejected by Newcastle for Yohan Cabaye on Monday, and as revealed by Goal, also enquired about Sevilla midfielder Geoffrey Kondogbia and made a £6m bid for Schalke right-back Atsuto Uchida.
Wenger is also weighing up whether to offer a one-year contract to Mathieu Flamini, who is training with Arsenal after being released by AC Milan at the end of last season.
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