CHAPEL HILL, N.C. — Trevor Lawrence sprinted downfield Saturday, hair flopping out the back of his helmet, not with the ball in his hands but with a spring in his step.

The Clemson quarterback had just found wide receiver Tee Higgins for a 38-yard touchdown with 9:54 left in the fourth quarter against North Carolina, the decisive blow in the No. 1 Tigers' 21-20 win. Lawrence weaved through the Tar Heels' dejected defenders, reached Higgins and embraced him with a chest bump. 

The Tigers survived in Chapel Hill, but just barely. Tar Heels running back Javonte Williams found the end zone on a 1-yard run with 1:17 remaining, and North Carolina went for the two-point conversion and the win.

The game was knotted at 14 at halftime, and neither team scored in the third quarter. It had been 364 days since Clemson last started a fourth quarter without the lead, when Syracuse held a 16-13 lead at Death Valley. Clemson went on to win that game, 27-23, but not without scaring its fan base.

"That team went on to win the national championship," Swinney said. 

On Saturday, North Carolina quarterback Sam Howell, who had already thrown two touchdowns, took the snap and rolled right on the two-point conversion attempt. He ran into a wall and was stopped, and the Tigers celebrated.

Clemson was favored by 27 points on the road, but coach Dabo Swinney urged against ruling out North Carolina. With Mack Brown, the Tar Heels' new coach and and one of Swinney's early mentors. on the opposing sideline, North Carolina proved Swinney right — and nearly put the Tigers' College Football Playoff hopes in jeopardy.

But then Lawrence found Higgins, and Clemson's defense delivered the stop of the season. Lawrence kneeled on the game's final play, running out the clock. He rose and threw both arms skyward, a winner once again.

"Ain't no reason to panic!" Swinney said. "We're gonna be alright."

What went right

For all of Clemson's inconsistent play on offense, Lawrence avoided committing any major mistakes. He completed 18 of 30 passes for 206 yards and one touchdown without throwing an interception. He also ran 11 times for 45 yards and a touchdown, while running back Travis Etienne compiled 67 yards and a score on 14 carries.

On defense, the Tigers prevented Howell from building on his hot start to the game, when he threw for a 40-yard touchdown on North Carolina's fourth play from scrimmage. Howell finished 15 of 27 for 144 yards. 

What went wrong

It took longer than expected for Clemson to put away the Tar Heels, in part because of mistakes and sloppy play. Etienne fumbled in the second quarter, leading to a North Carolina score. 

That wasn't all. The Tigers committed six penalties for a total loss of 30 yards; they were 8 for 15 on third downs and failed to convert their lone fourth- down attempt; kicker B.T. Potter missed his lone field goal attempt.

It all prevented Clemson from going on the type of run that has defined its season so far, and it almost led to an upset. 

"Today was a tough day at the office," Swinney said. "No doubt. Fortunate win. Very blessed to be able to win this game." 

Turning point

Swinney accidentally knocked down the pylon late in the fourth quarter when he sprinted down the field to call a timeout. North Carolina scored on the next play anyway and Kenan Memorial Stadium erupted.

All Lawrence could do was watch from the sideline as the Tar Heels lined up for the two-point conversion.

"You would like to feel like you could do something, have control of it," Lawrence said. "I didn't have any doubt, though. As soon as they scored I was like, 'we're going to stop them here.'"

With the game on the line, Clemson's defense swarmed Howell. The Tar Heels had converted 3 of 6 third-down attempts and 2 of 3 fourth-down attempts in the fourth quarter, but in the end, the Tigers landed the final blow. 

Looking ahead 

The Tigers have an open date before returning to Death Valley to host Florida State on Oct. 12. 

Follow Joshua Needelman on Twitter at @joshneedelman.

Joshua Needelman covers Clemson for The Post and Courier. He's a Long Island, N.Y., native and a University of Maryland graduate.