Barnes set a freshman tournament record with 40 points to help North Carolina rally past Clemson 92-87 in overtime in the semifinals, sending the Tar Heels back to the championship game for the first time in three years.
Barnes hit the go-ahead 3-pointer with 4:13 left as part of a 9-0 spurt to open the extra period for top-seeded North Carolina (26-6), which continued its living-dangerously run in Greensboro with another big comeback. A day after rallying from 19 down in the final 10 minutes to beat Miami, the Tar Heels trailed the Tigers (21-11) by 14 in the first half and rallied from seven down in the final 4 minutes of regulation to force overtime.
"My goal was to be in the final," Barnes said. "This is not how I imagined us doing it, but we find a way."
The Tar Heels have won 19 of 21 games since losing to Texas on a last-second shot in December here. They're now a win away from their 18th ACC tournament title, which would tie Duke for most all-time. They'll face the fifth-ranked Blue Devils in Sunday's final, marking the first time the fierce rivals have met for the title in 10 years.
Barnes finished 12 of 17 from the floor and went 10 for 11 from the foul line, capping his day with two free throws with 8.3 seconds left and the Tar Heels ahead 90-87.
His 40 points also tied former UNC great Tyler Hansbrough for the league's freshman scoring record in any game, stood as the first time a player had scored 40 in the tournament since Wake Forest's Randolph Childress in 1995 and was the most by a North Carolina player in the tournament since Charles Scott had 41 in the 1970 quarterfinals.
It was fitting that Barnes' big performance happened here, on the same court where he hit a tying 3 in the final seconds of the loss to the Longhorns. Barnes had struggled with his shot early, but that basket started a run of clutch late-game shooting for the player widely regarded as the nation's No. 1 recruit.
"Early in the year, the young man took a lot of doubters and criticism from people who said, 'Oh, he's not that good,"' coach Roy Williams said. "He just stayed focused on being Harrison Barnes."
Barnes capped the OT-opening run with a three-point play, then added his sixth 3-pointer to beat the shot clock with 1:14 left. That shot came after the Tar Heels had gotten an offensive rebound and as Williams was calling to reset the offense, prompting Williams to joke that the shot saved his team from bad coaching.
"You know, Coach and I have been back and forth between play calls and my shot selection," Barnes said. "I've been in the situation where I've missed it before and I've come out alive, so I figured why not try again?"
Demontez Stitt scored a career-high 25 points to lead the fourth-seeded Tigers, who appeared in good position to reach their third final by shutting down Kendall Marshall and the UNC transition game through the first half. But Barnes single-handedly kept North Carolina in it with 16 first-half points, then kept making big shots to thrill a home-state crowd filled with plenty of light blue.
Going back to the regular season, Barnes hit the go-ahead shots in the final 5 minutes of regulation or overtime in all three games against the Tigers.
"We couldn't guard him, couldn't stop him," Clemson coach Brad Brownell said. "He was a real difference-maker for them."
A day after they didn't take a lead until Tyler Zeller's layup at the final buzzer, the Tar Heels led for all of 36 seconds in regulation. They rallied to take a one-point lead on Zeller's basket midway through the second half only to see Tanner Smith answer with a 3-pointer to put Clemson back in front.
Smith added another huge 3 with 4:37 left to push the lead to 72-66, but the Tigers didn't manage another basket in regulation. That gave the Tar Heels their opening, with Barnes cutting the gap to 73-71 on a 3 over Milton Jennings before Zeller scored on a hook shot in the lane over Jerai Grant to tie it with 45 seconds left.
Stitt missed a contested shot as the horn sounded on regulation, and Barnes soon put the Tar Heels ahead for good.
Now, the Tigers must wait to learn if they have done enough to reach the NCAA tournament. They rolled past Boston College in Friday's quarterfinals, but let a huge win slip away Saturday despite shooting 50 percent and going 12 for 24 from 3-point range.
"I don't know that I need to make an (NCAA) argument," Brownell said. "If I need to make an argument, people aren't watching."
Clemson fell to 1-15 against North Carolina in the ACC tournament and 0-18 all-time against the No. 1 seed.