TAMPA, Fla. -- Tennessee Tech wide receiver Drew Hixon was upgraded Friday from critical to serious condition but remains unconscious 13 days after he was injured in a game. Hixon, the son of Washington Redskins assistant Stan Hixon, had been in critical condition at St. Joseph's Hospital since being tackled in a helmet-to-helmet collision and carried off the field during the Sept. 11 game with South Florida. Hixon was taken off a ventilator Friday morning and is breathing on his own but remains in intensive care, hospital spokesman Will Darnell told The Associated Press. Hixon's father told Darnell that doctors think that Hixon is improving but that the recovery process will take a long time. Doctors have told the Hixon family that the 22-year-old senior could regain consciousness at any time. Hixon transferred to Tennessee Tech from LSU, where his father was an assistant coach last season. Tennessee Tech plays at Murray State on Saturday