England prop Phil Vickery is battling to be fit for the Six Nations Championship opener against France at Twickenham on Saturday week.
The Gloucester captain has missed his club's last two games because of a back problem and is unable to train.
"I am in pieces with it at the moment," he said. "The back has not been good for a while because of stiffness. But during the team run before the Powergen Cup match with Saracens the weekend before last I stumbled off balance and that was it, game over.
"I have had bangs before but nothing serious. I am having an X-ray today and seeing a specialist tomorrow to make sure it is not a disc problem."
Gloucester coaching director Nigel Melville says Vickery is unlikely even to be considered for England's game if he cannot turn out for the Cherry and Whites against Bath this weekend.
Vickery's injury compounds England's front row problems.
His Gloucester and England team-mate Trevor Woodman is still recovering from surgery, Bristol prop Julian White went off with a knee injury in a game two days ago, and Saracens's David Flatman is unlikely to play again this season.
PA