CHARLOTTE—Zion Williamson's absence could be used as an excuse in the regular season, a way to make Duke feel better about getting swept by North Carolina for the first time since 2009.

Those defeats were largely erased with a gritty victory in the ACC tournament, with Williamson of course leading the way. 

The third-seeded Blue Devils beat No. 2 seed North Carolina 74-73 in an ACC semifinal for the ages at the Spectrum Center, rallying from an early 13-point deficit to make it tight throughout the second half. Williamson followed up his 29-point, 14-rebound game in the quarterfinals with another titanic performance, finishing with 31 points and 11 boards.

The freshman forward scored the game-winning bucket, out-leaping Nassir Little and Luke Maye to follow his own miss with a two-handed tip-in with 31 seconds left.

"Why would I pass up on this experience, playing in the biggest rivalry ever? You can’t go create moments like that nowhere else," Williamson said. "I feel like I have a really great second jump, and that’s just my competitive spirit, so when I saw it miss, my instinct was to try to just get the rebound."

Cameron Johnson had a good look at a 3-pointer on the next play but didn't convert it, and R.J. Barrett missed a pair of free throws to leave the door wide open with 12 seconds left. The building could finally exhale when Coby White's fadeaway 3-pointer in the closing seconds rimmed out and Little couldn't quite control a desperation tip-in.

"I knew by the way he was sizing me up he was trying to get off a three. I felt like I took him out of his rhythm there a little bit," Duke point guard Tre Jones said. "I felt like I forced him into a pretty tough shot, even though sometimes those are the ones that go in."

White's misfire was a fitting finish to an ice-cold night for the Tar Heels, who shot just 4-of-27 from long distance. North Carolina scored only 29 points in the second half, struggling to deal with tenacious defense from Jones, Williamson and reserve point guard Jordan Goldwire, who played a career-high 28 minutes.

The Tar Heels went scoreless for more than four minutes to let the Blue Devils turn a two-point deficit into a two-point lead, but finally broke through to pull in front on a fast-break 3-point play for Johnson with three and a half minutes remaining. Maye finished through contact on the North Carolina's next possession as well, but an and-one for Williamson and a layup by Goldwire after recovering a loose ball put Duke in front 72-71. 

Nassir Little then came through the lane for a dunk with 48 seconds on the clock to give the Tar Heels a one-point lead before Williamson contributed the eighth and final lead change of the night.

After trailing for almost the entire first half, the Blue Devils (28-5) battled back to even it up at 44-44 heading into the locker room and quickly scored six straight points to seize their largest lead out of the break. The biggest pro-Duke roar of the night to that point came on an and-one for Cam Reddish as he powered through Maye for an and-one bucket leading into the second half's under-16 timeout.

Three straight turnovers and back-to-back Little dunks soon brought the louder North Carolina faithful to its feet to tie it up, and the two teams traded punches the rest of the way in an electric environment—a Williamson tomahawk dunk on one end, a Kenny Williams 3-pointer on the other, and back and forth they went.

"It's a long game, and they're going to play fast and we'll play fairly fast, not as fast as them, and we just needed some stops," Duke head coach Mike Krzyzewski said. "Vintage ACC, Duke-North Carolina, you know, both teams played so hard and well."

North Carolina (27-6) was the cleaner, crisper team for the first 10 minutes of the game, beating Duke down the floor repeatedly in transition and making almost every shot it took. Johnson scored the Tar Heels' first eight points of the game and had 16 in the first half as they raced out to a 33-20 lead.

But Williamson started Duke's rapid comeback with a 3-pointer with 6:01 left before the break and finished it with another triple to tie it up in the final minute of the half. After missing their first seven attempts from beyond the arc, the Blue Devils made four of their next five, and in between Williamson's 3-pointers, some unlikely suspects helped the Blue Devils battle back.

Goldwire and senior Antonio Vrankovic both came off the bench to play significant minutes, slowing the Tar Heels down with their defense and each making a layup during Duke's first-half comeback. Vrankovic and Goldwire did well enough that their effort earned them spots as starters when the Blue Devils took the floor for the second half.

"They deserved to start. They put us in a position to do that. I don't think it was desperation as much as who do we have in uniform?" Krzyzewski said. "We had a big meeting this morning about giving energy and anyone who is in the—give the guys who have been in the game a long time energy."

The Blue Devils will return to the ACC championship game Saturday night for the second time in three years, meeting up with No. 4 seed Florida State, which upset top-seeded Virginia earlier Saturday night 69-59. The Seminoles have not played for an ACC title since 2012, when they took home their only conference crown.

"Just a year ago, my high school season was already over. I was probably getting ready for the McDonald’s All-American game, and a year later, playing for an ACC championship, life can change drastically in one year," Williamson said. "You’ve just got to live in the moment."