"Theo dislocated his shoulder during training. He will be out for at least three months," Arsenal manager Arsene Wenger told TF1 television channel.

Walcott has earlier sustained a minor injury problem which kept him out of Arsenal's UEFA Champions League clash against Fenerbahce on November 5th.

The injury is a massive blow for the player, who already underwent a shoulder surgery, which kept him out for few months last season.

The injury is set to hinder Walcott's progress this season, after the 19-year-old earned a regular place in Fabio Capello's England set up, following some impressive displays for Arsenal since the start of the season.