GREENSBORO, North Carolina (Ticker) -- Jarrett Jack made Roy Williams' first coaching appearance in the Atlantic Coast Conference tournament a short one.

Jack's jumper with less than two seconds remaining lifted 18th-ranked Georgia Tech to an 83-82 triumph over Williams and No. 19 North Carolina in the ACC tournament quarterfinals.

Georgia Tech (23-8) had a 73-62 lead after Luke Schenscher made a pair of free throws with 6:16 left but allowed North Carolina to storm back.

Sean May made the second of two free throws with 10 seconds left to give the Tar Heels an 82-81 lead. After two timeouts, Jack inbounded the ball at half-court to Marvin Lewis, who gave it back to Jack. He beat Rashad McCants with a crossover dribble at the top of the 3-point arc and nailed a 14-foot jumper.

"We drew a play to get Isma'il Muhammad a lob on the backside, but I didn't think he was quite open," Jack said. "When I threw it in to Marvin, they left me and their defense was kind of scrambling. I just tried to find a way to get myself open and make something happen going to the basket.

"I knew the clock was ticking down and I just tried to make a play and luckily, the shot went in.

After a quick inbounds pass by May, Lewis stole the ball from McCants to end the game.

"It was what you dream about - coming to the ACC tournament and being the hero, knocking down a shot to help your team move on to the next round," Jack said.

Jack finished with 17 points and six assists, Schenscher added a career-high 17 points and 17 rebounds and B.J. Elder scored 16 points for Georgia Tech, which advanced to the semifinals for the first time in three years.

The Yellow Jackets, who have won four in a row, will play top-seeded Duke on Saturday. They snapped the fourth-ranked Blue Devils' 41-home winning streak with a 76-68 victory on March 3.

May scored 27 points, McCants contributed 25 and Raymond Felton had 20 for the Tar Heels (18-10), who should make their first NCAA Tournament appearance in three years.

Williams, who tasted success in the ACC tournament while an assistant coach under Dean Smith, is in his first season at the helm in North Carolina. He watched his team use a 17-4 run to erase a double-digit deficit in the second half and take a 79-77 lead with 2:36 left.

"We were down by 11 and I was pleased and impressed by our team by the way they fought and made plays and shots and steals," Williams said. "They played basketball like I've seen them play several times during the season."

Felton had five points in the burst before aggravating a right hip injury suffered in Saturday's loss to Duke.

"With Felton banged up, it would have been easy for them when they got down by 11 to pack it in and play for next week," Georgia Tech coach Paul Hewitt said. "But they picked it up on defense and got us out of our flow offensively."

Jack drained two free throws to tie it, 79-79, before May converted two from the stripe to put the Tar Heels ahead with 2:10 to go. Clarence Moore knotted it again with a layup with 1:53 left.