Mike Glennon threw three touchdown passes and the Wolfpack shut down the Tigers' explosive offense to take a 37-13 win on Saturday, a surprisingly dominant performance by a team still trying to become bowl eligible.
Tobais Palmer had a dazzling 43-yard catch-and-run touchdown to highlight a big night for NC State (6-5, 3-4 Atlantic Coast Conference). The Wolfpack scored 27 points in the second quarter, then increased the lead and never let the Tigers (9-2, 6-2) build any momentum to rally.
"I really have no explanation for what just happened," O'Brien said with a smile.
It was NC State's first win against a top-10 team in five seasons under O'Brien and it continued the mystifying ways of a team that has struggled with consistency all year.
The Wolfpack followed a shutout win against rival North Carolina with an inept performance in last week's loss at Boston College. Yet NC State responded by emphatically ending a seven-year losing streak to a team that had already wrapped up the league's Atlantic Division crown and an appearance in the ACC championship game in Charlotte on Dec. 3.
NC State still needs to win next week against Maryland to become bowl eligible, which was why O'Brien wasn't laughing when his players celebrated by dumping a cooler on him -- twice -- late in this one.
"As I said to the team, the biggest thing is here we are again in this situation," he said. "That's the biggest question that has to be answered right now, that you can't have a big win and then not play the next week."
Still, he couldn't have asked for much more. His players avoided turnovers, made few mistakes and seemingly had the perfect counter for anything Clemson tried to do. And the defense -- which had held the past two opponents to fewer than 200 total yards -- harassed Tajh Boyd and cut off the big plays that had made the Tigers' offense hum.
The Tigers averaged a league-best 37 points and 478 yards per game, but they didn't reach the end zone until the final 90 seconds. They didn't crack the 200-yard mark until late in the third quarter and earned many of their 337 total yards in the meaningless final minutes.
"To be honest with you, I don't care who we face -- I feel we can blow them out," linebacker Terrell Manning said. "I feel like we have one of the better teams in the ACC. We may not show it all the time, but when we do, we do."
Clemson coach Dabo Swinney had said he wanted his players focused on "trying to go from good to great" as they pursued the program's first 10-win season since 1990. Instead, the Tigers turned in a jarring clunker heading into a rivalry game at No. 14 South Carolina next weekend.
"I'm disappointed in how we played, "Swinney said, "embarrassed really."
Swinney said he thought his players were ready despite having nothing to gain in the standings. But they committed four turnovers, including two second-quarter fumbles deep in their own end that led to 10 quick points and charged up the red-clad Wolfpack crowd hoping for an upset.
Clemson now has 11 turnovers in the past three games, losing two after an 8-0 start.
"We looked like an immature team out there tonight," Swinney said. "That's really it in a nutshell."
Clemson played without star freshman receiver Sammy Watkins due to a shoulder injury suffered during last week's division-clinching win against Wake Forest. Swinney decided to be cautious, so Watkins spent this game in uniform on the sideline.
While Watkins' absence robbed the Tigers of some of their big-play punch, it didn't explain why an NC State offense that had scored 23 points in the past three games moved the ball so effectively.
Glennon completed 19 of 29 passes for 253 yards, with scoring passes to George Bryan and Jay Smith during the big second quarter.
By the time Niklas Sade kicked the second of three field goals to close the first half, NC State led 27-3 and sent the stunned Tigers to the locker room.
NC State finished with 398 total yards and held the ball 13 minutes longer by sustaining drives and keeping Clemson's offense on the sideline.
"We knew what was at stake," Glennon said. "We knew this was a great opportunity to play the No. 7 team in the country and beat them."
The Tigers managed just 86 yards through the first half. Meanwhile, NC State's defense finished with six sacks -- 2½ coming from Art Norman -- while Manning recovered a pair of fumbles and teamed with Audie Cole to run Boyd out of bounds short of the marker on fourth down to end Clemson's first drive after the break -- a sign there would be no second-half comeback.
Palmer later provided the Wolfpack's highlight-reel moment, taking a short pass from Glennon and sprinting down the left sideline. As two would-be tacklers closed in, the receiver abruptly cut inside and raced past them into the end zone for the 37-6 lead with 5:41 left in the third.
Boyd threw two interceptions near the end zone later in the period, with NC State sophomore David Amerson snatching one on fourth down at the goal line to tie the ACC single-season record with 11 picks.
"Maybe the mentality shifted a little bit, maybe it's about finding ourselves," Boyd said. "The coaches can coach us up, but as players, we have to come out here and want it, too."