Arsenal face Manchester United at the Emirates Stadium on

Theo Walcott has suffered another injury setback, ruling him out of Saturday's Premier League showdown against Manchester United.

The Arsenal forward has only just come back from fitness following a nine month lay-off with a serious knee injury.

But Walcott has now returned from England duty with a groin problem.

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Theo Walcott, pictured ahead of England's game against Scotland, has returned to Arsenal with a groin injury

Walcott, in training for England last week, has only just returned from a nine-month injury lay-off

Danny Welbeck, pictured celebrating Wayne Rooney's second goal against Scotland, is an injury doubt

'Theo is not available for tomorrow's clash, he has a tight groin,' said Wenger.

Walcott's team-mate Danny Welbeck is also a doubt for the game after picking up a hamstring injury whilst on international duty.

Wenger added: 'We will decide of Welbeck is fit after checking on him today.'

Fit-again striker Olivier Giroud can, however, help offer Arsenal 'different options', according to Wenger.

The France international has recovered quicker than expected from a fractured leg suffered when challenging for the ball in the closing stages of the 2-2 draw against Everton on August 23.

Olivier Giroud has returned to training for Arsenal and could feature against Manchester United

The Frenchman has been sidelined after he suffered a fractured leg in the draw at Everton back in August

Football analysts Bloomberg Sports believe an Arsenal win is the most likely outcome against Man Utd

Wenger revealed Giroud could even be involved in the game against United at the Emirates Stadium, although the trip to West Brom on November 29 looks a more realistic target.

The Gunners boss is confident when he and Walcott are fully match fit, the Arsenal squad will have even more firepower at their disposal to add to the impressive form of summer signing Alexis Sanchez and former United frontman Welbeck.

'Giroud and Mikel Arteta are both available. It is just a question of how ready they are, but they are available,' said Wenger to the club's website.

'He (Giroud) is three or four weeks ahead of schedule. Originally we planned to have him back for competition at the beginning of next year, so he is one month ahead.'