Watson, who returned as a starter for the Tigers (No. 19 CFP, No. 18 AP) after missing three games with a broken bone in his right hand, was hurt when making a cut late in the first quarter of Saturday's game. Watson ran for 7 yards and a first down before falling to the ground and grabbing his left knee.
Watson, a freshman, walked off the field and was escorted to the locker room. Coach Dabo Swinney said after the game that ligament damage is a possibility.
QB Deshaun Watson (knee) is officially out for the rest of the game.
— Clemson Football (@ClemsonFB) November 15, 2014
"He just planted," Clemson coach Dabo Swinney said after the game. "Just unbelievable. ... That was a tough loss for us, but we don't make any excuses."
Entering the game, Watson was averaging 10.5 yards per pass attempt this season -- the highest rate in the FBS among players to attempt at least 100 passes. Tajh Boyd set the Tigers' single-season record for yards per pass attempt just last season with 9.3.
he threw two more interceptions, including another returned for a touchdown.
Stoudt, who began the season the starter before getting benched in favor of Watson on Sept. 20, won all three games while Watson was out, but did so while turning the ball over four times and accounting for only four touchdowns.
The Associated Press contributed to this report.