CLEMSON, S.C. - From the moment the shot rolled off Wayne Ellington's fingertips, he knew North Carolina would survive their toughest challenge so far this season and return home with its No. 1 ranking intact.

North Carolina's Wayne Ellington (22) shoots as Clemson's Demontez Stitt, left, tries to block the shot during the first half of their basketball game Sunday, Jan. 6, 2008, at Littlejohn Coliseum in Clemson, S.C. (AP Photo/Mary Ann Chastain)

Ellington's 3-pointer with 0.4 seconds left in overtime lifted the Tar Heels to a 90-88 victory over 19th-ranked Clemson in the team's first Atlantic Coast Conference game of the season for both teams Sunday night.

After weeks of routing nonconference competition — they had won their previous four games by an average of 33 points — North Carolina (15-0) found itself locked in a classic. The Tar Heels came out on top, and with a few lessons on how to hang tough in close games.

"It shows our maturity, it shows we can stick it out and get the win when we have to," Ellington said.

North Carolina's Tyler Hansbrough said the team was lucky to survive Clemson's challenge.

"We didn't do the things we needed to do defensively at times," Hansbrough said. "But it's still young in the season and we've got time to make improvements. Hopefully, at the end of the year when we come into these situations, we'll be more prepared."

Ellington scored a career-high 36 points, shooting 5-of-8 from 3-point range and 9-of-9 from the foul line.

The 19th-ranked Tigers (12-2) showed they could compete with the ACC's best. Clemson led 81-74 with 2:37 left, the Tar Heels' largest second-half deficit this year, before North Carolina outscored them 7-0 down the stretch to force OT.

The Tigers were up 86-83 in the extra period on David Potter's bucket with 1:33 to go, but Ellington and Lawson hit two foul shots each to send North Carolina back in front.

Clemson freshman Demontez Stitt then made two free throws with 13.9 seconds remaining to give the Tigers an 88-87 lead, sending the crowd into a frenzy. Ellington's dramatic shot quieted things down.

"It felt really good," Ellington said. Defender James Mays was "flying at me and I knew if it had chance to get there it was going to go in," Ellington said.

The Tar Heels leaped from the bench as Ellington pumped his fist in celebration.

It was North Carolina's first OT victory since defeating Georgia Tech during the 1999-2000 season.

"It wasn't the prettiest game in the world," North Carolina coach Roy Williams said. "But it was a game by two teams that fought very hard."

As usual, the Tar Heels came out on top.

They've won seven straight in the series. Clemson will get another chance in the regular season, but that game is in Chapel Hill, where the Tigers are 0-52.

Clemson coach Oliver Purnell was left shaking his head about missed opportunities.

The Tigers were 14-of-27 on free throws and 6-of-24 on 3s. The Tigers had 11 blocks but were outrebounded 50-45.

"We talked about taking care of small details that come back to haunt you," Purnell said. "It's never just one play."

Ellington scored seven of North Carolina's nine points in overtime. He surpassed his career high of 23, set earlier this season in a win over Ohio State.

Purnell was pleased with Clemson's defense on Hansbrough, who was held to 12 points, 10 fewer than his average. Hansbrough led North Carolina with 14 rebounds.

"If you told me we're going to that job on Hansbrough, I'd feel pretty good," Purnell said.

Ellington was another story.

"I didn't think he'd get 36," Purnell said. "33 would've been fine."

K.C. Rivers led Clemson (12-2) with 24 points, but didn't score in overtime. Trevor Booker added 14 points and 11 rebounds.