The brilliant 19-year-old midfield star faces being out until February after an operation to repair the right ankle he damaged in pre-season.
The news was also a hammer blow for England manager Fabio Capello, who is hoping to build his Euro 2012 midfield around Wilshere's talent but must now wait to monitor his recovery with the clock ticking down to when he names a squad. Wilshere first collected the problem a stress fracture while on England duty in the 2-2 draw with Switzerland at Wembley in June.
Bed ridden: Jack Wilshere had surgery on his right ankle and will now miss five months
Arsenal, who had campaigned for him to be left out of Stuart Pearce's squad for the Under 21 European Championship, believed a summer's rest would cure him but he aggravated the injury when playing in a friendly at the end of July.
The club then hoped that a spell in a protective boot would enable the teenager to return before Christmas, but an Arsenal statement revealed that his rehabilitation will take 'four to five months'.
The statement said: 'Under the care of two world renowned surgeons, Jack has had the stress fracture of his right ankle repaired.
Jack's the lad: Wilshere is extremely unlikely to play again in 2010
The initial indications are that the surgery has been successful and Jack will now undergo a prolonged period of rehabilitation.
'It is envisaged that Jack's rehabilitation will take a period of four to five months.'
Wilshere added on Twitter: 'Had my operation and all went well! I am feeling good will spend the night in hospital to monitor me but apart from that I am happy!'
While Wilshere might have been happy, manager Wenger certainly will not have been after a summer in which he has seen his midfield broken up by the departures of skipper Cesc Fabregas to Barcelona and France midfielder Samir Nasri to Manchester City.
Sitting it out: Wilshere will also miss several games for England
Even Saturday's 3-0 win over Bolton brought mixed feelings as new captain Robin van Persie, who scored two of the goals to take his tally for the club to 100, promptly admitted he does not want to start talks about a new contract.
And the home Champions League tie with Olympiakos will bring the focus firmly back on the Gunners after an indifferent start to the campaign that has left them in the bottom half of the table after half a dozen Premier League games.
At least there was some good news as Theo Walcott has been cleared to play both against the Greek champions and also in Sunday's north London derby against Tottenham at White Hart Lane.
Walcott had to be helped off the pitch at the end of the win over Bolton, but scans to both his knee and hamstring showed no more than severe bruising.
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