West Ham's England international midfielder Kieron Dyer has suffered a double fracture of his right leg, the Premier League club confirmed on Wednesday.
The 28-year-old, who was making only his third appearance since his £7 million pound move from Newcastle, crumpled to the turf after Rovers' Joe Jacobson shoulder-charged him during West Ham's 2-1 win over Bristol Rovers in the League Cup second round on Tuesday.
West Ham said in a statement that Dyer had broken both the tibia and fibula of his right leg.
"It is too early to say at this stage how long the player will be out for as this will become clearer once the first stage of surgery is completed," the club said.
West Ham manager Alan Curbishley accused Jacobson of "lashing out" at Dyer.
Curbishley said: "We're devastated for Kieron. I can't put it into words. The game was just immaterial after that.
"The player has got to be disappointed with his tackle. As far as I could see, he lashed out after losing the ball."