Tony Goulet, a Valencia High School running back who was injured in the second quarter of the Tigers' 33-10 victory over Bolsa Grande last Friday, suffered torn ligaments in his left knee.
Goulet was taken to Humana Hospital in Westminster, where a cast was put on.
"There's no telling about whether he'll return this season, but right now it's doubtful," said Frank Goulet, Tony's father.
Goulet was The Times' Player of the Week earlier this month after Valencia's 41-0 victory over El Dorado. In that game, Goulet rushed for 176 yards in 12 carries, including 5 touchdowns.