The No. 9 Clemson Tigers entered the 2023 college football season with its worst preseason ranking since 2015. 

The Tigers may be out of the rankings after a brutal Week 1 performance. 

Riley Leonard runs against Clemson

Nate Wiggins, #2 of the Clemson Tigers, attempts to tackle Riley Leonard, #13 of the Duke Blue Devils, as he runs the ball during a football game at Wallace Wade Stadium in Durham, North Carolina, on Sept. 4, 2023. (David Jensen/Icon Sportswire via Getty Images)

The Duke Blue Devils upset Clemson 28-7 Monday night, beating its first top-10 team since 1989, in a turnover-filled mess for the Tigers. 

DUKE'S RILEY LEONARD PLEADS FOR EXTENSION ON HOMEWORK AFTER UPSET WIN OVER CLEMSON

Dabo Swinney brought in Garrett Riley to run the offense after he was named the Broyles Award winner, given to the top assistant in college football, in 2022. Cade Klubnik, a former five-star recruit, officially took over the reins at quarterback after the Tigers struggled at the position in 2022 with DJ Uiagalelei

The changes were supposed to put Clemson back on track after missing out on the College Football Playoff the past two seasons. 

Instead, the Tigers turned the ball over twice inside the Blue Devils 10-yard line in the second half and missed two field goals for Clemson’s worst ACC loss since 2014. 

"It's almost indescribable what I just saw," Swinney said, according to ESPN. "It's incredibly frustrating when you had so much opportunity. ... It's routine stuff. The basics. The fundamentals. Basic, basic stuff."

Dabo Swinney coaches against Duke

Clemson Tigers head coach Dabo Swinney looks at the scoreboard during the fourth quarter against the Duke Blue Devils at Wallace Wade Stadium in Durham, North Carolina. (Ken Ruinard-USA TODAY Sports)

The Tigers had multiple chances in the second half to take back the lead after falling behind 13-7 early in the third quarter. 

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On a first-and-goal from the Duke seven-yard line late in the third, Klubnik mishandled a zone read, giving the ball back to the Blue Devils. 

At the start of the fourth quarter, Clemson running back Phil Mafah fumbled on a first-and-goal from the one-yard line, with Duke’s Jaylen Stinson rumbling to the Clemson 33-yard line.  

"That's the weirdest game I've ever been a part of," Swinney said, per ESPN. "I've been beat. I've had my butt kicked. But that's the strangest game I've ever been a part of."

For Duke, the opening weekend win comes after a nine-win season in Mike Elko’s first season in Durham. 

"It’s important on the outside, because I think it makes people believe a little bit more what we’ve been saying since the day I got here," Duke's second-year coach said. "What we’ve been saying internally is this is what Duke football is capable of. We’ve never ever wavered from that at all."

Vincent Anthony Jr. celebrates play

Vincent Anthony Jr., #19 of the Duke Blue Devils, reacts following a defensive stop against the Clemson Tigers during the first half of the game at Wallace Wade Stadium on Sept. 4, 2023 in Durham, North Carolina. (Lance King/Getty Images)

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Duke quarterback Riley Leonard was just 17-33 for 175 yards, but the junior rushed for 98 yards on the ground, including a 44-yard scamper at the start of the second half to give the Blue Devils the lead for good. 

Clemson has now lost two of its last three season openers.

"We’re not entitled to win," Swinney said. "We’ve got to go earn it. And we had plenty of opportunity to get control of that game on multiple occasions and we just didn’t. And that's how you get beat."

The Associated Press contributed to this report