"Graham's ankle looks to be a serious injury and his status for the rest of the season is very much in question," Bucs Coach Jon Gruden said at a Monday news conference. "His season could be in jeopardy right now."
Graham, a 5-year veteran, was injured on his first carry of the game and had to be helped to the sideline. After being attended to by trainers, he was taken to the locker room for further examination.
He had been nursing a knee injury in the week prior to the game.
Graham's injury means Carnell "Cadillac" Williams, who was activated early last week, will see extended time at running back for Tampa Bay. Williams has not played an NFL game since Sept. 30, 2007. He returned to practice late last month.