Tests have confirmed the midfielder did have a problem, which was feared could be a hernia.Should further assessment back that up, the 23-year-old would likely require surgery that would end his season.
Noble left the field on a stretcher an hour into Saturday's 3-0 defeat at Chelsea after going down with pains in his lower stomach. He had already missed six weeks this term with appendicitis and has had groin problems in the past.
At full stretch: Mark Noble could be ruled out of City's game after tests confirmed he did have a stomach injury
Losing him would be another massive blow to West Ham's survival hopes, with fellow midfielders Scott Parker and Gary O'Neil also currently sidelined.
Parker is unlikely to return until after Sunday's game, having already missed the last two matches with an Achilles problem, while O'Neil's season is over because of a serious ankle injury.
That would mean another start in midfield for Jonathan Spector, who had been known primarily as a defender until this term.
West Ham's Spector looking to repeat survival trick of 2007 Great Scott! Parker could return to face Man City for relegation strugglers West Ham WEST HAM FC