By AARON BEARD, AP Basketball Writer

CHAPEL HILL č North Carolina finished off its fiercest rival and the Atlantic Coast Conference regular-season race with one strong performance.

Harrison Barnes scored 18 points to help No. 13 North Carolina beat No. 4 Duke 81-67 on Saturday night, clinching the ACC championship and the top seed in next week’s league tournament.

Kendall Marshall had 15 points and 11 assists as the Tar Heels (24-6, 14-2) ended a three-game losing streak to their fierce rival and earned the top seed in next week’s ACC tournament. North Carolina also avenged last month’s loss at Cameron Indoor Stadium in which the Tar Heels blew a 16-point lead in the first half.

Once again, the Tar Heels built a big lead in the first half, this time 14 points. But Barnes and the Tar Heels protected that margin Saturday and stayed in control the entire night in a game that had tension and energy befitting a postseason game.

Nolan Smith scored 30 points for Duke (27-4, 13-3), while Seth Curry had 20 points with six 3-pointers.

In many ways, it was a replay of the first meeting for the Blue Devils.

Just as before, Smith and Curry completely carried the offense while Kyle Singler struggled to make much of anything while matching up much of the night against Barnes č the heralded recruit who picked North Carolina over Duke and other schools to cap a highly publicized recruiting battle.

But Barnes was more aggressive than he was in the first meeting, leading an offense that shot 52 percent č the highest Duke had allowed in any league game this season. Barnes went just 3 for 8 and had nine points in the first game, but went 7 for 17 to go with five rebounds in this one.

In addition, Marshall was in complete control of North Carolina’s offense, repeatedly pushing ahead in transition to set up plenty of good looks that allowed the Tar Heels to maintain a comfortable margin against the cold-shooting Blue Devils.

And when it was over, fans and students rushed onto the court to celebrate a surprisingly dominant victory against the reigning national champions. In fact, North Carolina coach Roy Williams had to address the crowd for them to clear off and allow his players to celebrate with his own tradition č clipping down the nets after clinching a league title at home.

Duke shot just 36 percent, including 6 for 27 from 3-point range. Singler, who shot just 3 for 17 in the first meeting, went 3 for 14 and missed all five 3-point tries while finishing with just eight points.

Now the Tar Heels will head into the ACC tournament seeking to continue their resurgence from that ugly 17-loss season of a year ago č which included two double-digit losses to the eventual national champion Blue Devils.

North Carolina has won 17 of 19 games since losing to Texas on a last-second shot in December, though it didn’t look much like a real challenger to the favored Blue Devils in the ACC race after looking lost in November losses to Minnesota, Vanderbilt and Illinois, and an ugly 20-point loss in January to lowly Georgia Tech.

But this group played defense well enough to keep its Hall of Fame coach happy all season and has been tough enough to win six games by three or fewer points. That included Wednesday night’s win at Florida State in which Barnes hit a 3-pointer in the final seconds for the 72-70 victory.

Surprisingly, there was little drama against Duke.

The Tar Heels led by 12 points at halftime and never let the Blue Devils get closer than five while avoiding a repeat of that second-half collapse at Cameron Indoor Stadium. Instead, they spent the final minutes of this one with the sellout crowd at an ear-ringing celebratory roar.