Newcastle keeper Steve Harper is expected to be out for three months after undergoing successful shoulder surgery.
Wednesday's surgery comes after the keeper was carried off on a stretcher in the first period of the 1-0 win at Everton on Saturday.
He was injured after a challenge by Jermaine Beckford, who was booked by referee Andre Marriner. Although the tackle was not a particularly bad one, the keeper came down heavily on his left shoulder and immediately looked in distress.
Newcastle have now confirmed the 35-year-old has undergone surgery and he faces an extended spell on the sidelines.
A statement on the club's official website said: "Following a shoulder ligament injury sustained in United's game against Everton on Saturday, Steve Harper has undergone a successful operation on Wednesday.
"It is likely Steve will be unavailable for selection for a period of around 12 weeks."
It means Harper is unlikely to figure for Newcastle's first team again until the middle of December - and is likely to mean an extended run in the side for Tim Krul.
Krul replaced Harper at Goodison Park and was also in goal for Wednesday night's 4-3 Carling Cup third round success over Chelsea at Stamford Bridge.
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