CLEMSON, S.C. -- Clemson coach Dabo Swinney has witnessed a lot of big-time performances from quarterback Deshaun Watson, but perhaps none bigger than the one he turned in Saturday night.

"Deshaun was unbelievable," Swinney said. "He played lights out."

Watson certainly flipped the switch on South Carolina, matching his school and Atlantic Coast Conference record with six touchdown passes to lead No. 4 Clemson to a 56-7 rout of rival South Carolina at Memorial Stadium.

Watson, a junior playing in his final home game in front of 81,542 fans, completed 26 of 32 passes for 347 yards, including four in the first half, as the Tigers bolted to a 35-0 lead and let the defense take over from there.

Clemson improved to 11-1 with its third consecutive victory over South Carolina (6-6) and will play Virginia Tech in the ACC Championship Game on Saturday in Orlando, Fla.

Clemson's offense was in high gear from the outset against South Carolina and set a school record with 40 first downs. The Tigers' 622 yards were their most ever against the Gamecocks and the 49-point margin represented the most lopsided victory in the series since 1900 when the Tigers won 51-0 in just the fifth meeting between the teams.

"I'm very happy for our players, especially our seniors," Swinney said. "For them to finish the regular season like this is incredible. This was a dominant performance. What a way for them to go out. They were ready from the opening snap."

Watson threw touchdown passes to cap each of Clemson's first two drives of the second half, then left the game for good with 4:38 left in the third quarter. His six touchdown passes were the most ever by a Clemson quarterback against South Carolina and matched the school record he set against North Carolina in 2014.

Three of Watson's touchdown passes went to junior wide receiver Mike Williams, who had scoring receptions of 34, 19 and 16 yards -- all in the first half. Williams, who finished with six catches for 100 yards, tied the school record for touchdown catches in a game shared by four others, most recently by DeAndre Hopkins of the Houston Texans.

Watson, who as a freshman in 2014 helped Clemson end a five-game losing streak against South Carolina by accounting for four touchdowns despite playing with a torn ACL, capped his career with another memorable performance against the Gamecocks.

In three career games against South Carolina, Watson completed 77 percent of his passes for 895 yards and nine touchdowns.

On Saturday, he became the third player in ACC history to be responsible for at least 100 touchdowns in a career with 104, joining former Clemson quarterback Tajh Boyd (133) and former North Carolina State star Philip Rivers (112).

But Watson had plenty of help against the Gamecocks. Running back Wayne Gallman rushed for 112 yards and a touchdown on 19 carries and wide receiver Artavis Scott had eight catches for 77 yards and a touchdown.

"Not a lot to say," South Carolina coach Will Muschamp said. "We got beat tonight by a better team; I don't know what else to say.

"They have a good team across all three phases. We got whipped. On the road recruiting -- that's the way we need to change our program."

Freshman quarterback Jake Bentley, who had guided the Gamecocks to a 4-1 record since taking over at midseason, was under relentless pressure and completed only 7 of 17 passes for 41 yards and an interception.

South Carolina was held to a season-low 218 yards and leading rusher Rico Dowdle had 30 yards on five carries.

The Gamecocks were unable to gain a first down until 12:37 left in the second quarter and managed only 52 yards and three first downs in the first half.

"We knew they weren't in our league," said linebacker Ben Boulware, who led Clemson with seven tackles, including two tackles for loss. "We knew we were going to go out there and dominate them."

Clemson did just that, early and often, en route to a 35-0 halftime lead.

After Clemson kicker Greg Huegel's 39-yard field goal attempt was blocked, the Tigers wasted little time opening the scoring on their second opportunity.

Clemson safety Jadar Johnson intercepted a Bentley pass on the Gamecocks' next play and the Tigers struck quickly, scoring three plays later on a 34-yard pass from Watson to Williams.

After forcing another three-and-out, Clemson drove 65 yards in 11 plays with Watson and Williams connecting again for a score, this time from 19 yards.

The Tigers then stuffed the Gamecocks on a fake punt attempt and extended the lead to 21-0 five plays later on an 11-yard touchdown pass from Watson to tight end Jordan Leggett.

Gallman added an 8-yard touchdown run with three minutes left in the half and Watson found Williams again with eight seconds in the half for a 16-yard score that extended the lead to 35-0.

In the third quarter, Watson had touchdown passes of 18 yards to running back C.J. Fuller and 3 yards to receiver Artavis Scott, and back-up quarterback Kelly Bryant added a 1-yard touchdown run in the fourth quarter.

South Carolina got its lone touchdown on a 33-yard pass from receiver Deebo Samuel to wide receiver Bryan Edwards with 11:24 left in the third quarter.

"We had some opportunities, but when you are in position, you have to make plays," Muschamp said. "Clemson is a very accurate team on all sides of the ball."

NOTES: Carlos Watkins leads Clemson with 7.5 sacks this season, the most by a defensive tackle since Trevor Pryce had 7.5 in 1996. ... RB Wayne Gallman needs 57 yards in the ACC Championship Game to eclipse 1,000 yards for a second straight season. ... South Carolina RB Rico Dowdle was held to 30 yards just one week after rushing for 226 -- the sixth-best total in school history -- in a win over Western Carolina on Nov. 19. ... South Carolina S D.J. Smith had a game-high 12 tackles. He is tied for the team lead with 72 stops this season.