Tottenham midfielder David Bentley has been ruled out for up to six months after knee surgery.
The 27-year-old former England international was trying to rebuild his career on loan at West Ham, where he has made five appearances since joining on transfer deadline day.
But he suffered the injury last week and has now gone back to White Hart Lane for treatment.
"It's a great shame for David as he had settled well in the squad," Hammers manager Sam Allardyce told the club's official website www.whufc.com.
"We wish him well and hope he has a speedy recovery."
Allardyce has recalled youngster Cristian Montano from his loan at Notts County as cover.
Tottenham said in a short statement: "David Bentley has undergone surgery to his left knee.
"The right-sided midfielder, who joined West Ham United on loan in August, is likely to be out for up to six months."