Mark Noble has been ruled out for up to a month after undergoing surgery for appendicitis.
The West Ham United No16 was seen by the club's doctor after suffering abdominal pains at Chadwell Heath on Monday.
The 23-year-old was taken to hospital and had his appendix removed during an hour-long procedure on Monday evening. Full recovery from an appendectomy usually takes around four weeks.
Noble has been in outstanding form this season, starting all ten Barclays Premier League matches and netting penalties against Bolton Wanderers and Wolverhampton Wanderers.
The midfielder also produced an outstanding display in helping the Hammers defeat Stoke City last week to reach the Carling Cup quarter-finals.