Reid, who was out for four weeks after Christmas with a hamstring problem that saw him miss three games, sustained the latest blow in the 1-1 draw at Portsmouth eight days ago.
'Unfortunately Andy has suffered a new hamstring injury,' confirmed club physician Dr Glen Rae on the club's official website. 'He is working with the medical team, but is likely to be missing from training for around four weeks.'
Crocked: Sunderland's Andy Reid (right) was injured against Portsmouth
Reid could potentially miss Sunderland's next five Barclays Premier League games, starting at Arsenal on Saturday before matches with Fulham, Aston Villa, Bolton and Manchester City.
Striker Kenwyne Jones, meanwhile, believes no-one can doubt his commitment to the Black Cats following a troubled January he has described as 'disturbing'.
Jones found himself continually linked with a move away from the Stadium of Light - most notably to Liverpool, who were apparently looking to sign the Trinidad & Tobago star on loan.
Jones is adamant he was not behind the stories, and was reassured to hear the soothing words of boss Steve Bruce during a troubling time.
Commitment: Kenwyne Jones (right)
'I didn't have any part to play in that whole situation,' asserted Jones in The Journal.
'There were stories going back and forth that were disturbing. There is no possible way you can avoid reading anything in the papers, but you try and lock yourself away from it as much as possible.
'If you noticed during all of this stuff I never came out and gave any indication I wanted to leave, that I was unhappy or anything like that.
'For me, that assumption is a bit far-fetched. There was a lot of stuff being said by whoever and you can't stop that.
'All I can do to prove I am committed to Sunderland is by showing it in games, and hopefully people can see it with their own eyes now.
'It's nice to hear the fans singing my name in the last two or three games, but I think they have been doing it most of the season.
'It's great to know they recognise that when I wear a Sunderland shirt I give it 100 per cent.
'I don't think the fans had any reason to believe I was behind these rumours, or that I wanted to leave.'
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