CHARLOTTE - The starting unit for the No. 2 seed Duke Blue Devils finished fast in its 82-70 victory over Georgia Tech on Friday in the quarterfinals of the ACC Tournament at Charlotte Bobcats Arena.

It's a good thing the starters finished so well because Duke had to win the game twice.

They had to win it once in the first half when the second unit sparked the Devils to a 15-point halftime lead, then again after halftime when the starters saw their 19-point lead shrink to one.

"I thought that we relaxed and they didn't," Duke coach Mike Krzyzewski said. "That's as much game pressure as we've had all year."

Off the bench, sophomore Jon Scheyer led the Devils with 18 points, and senior DeMarcus Nelson added 17 points, nine boards and seven assists to send Duke (27-4) to a semifinal game at approximately 4 p.m. today against No. 3 seed Clemson, which defeated No. 11 seed Boston College 82-48 on Friday night.

Georgia Tech (15-17) probably will not play further in the postseason.

The Yellow Jackets always feature athletes willing to play physical and still run teams down the court. But they couldn't body up on guys when the Devils were blocking shots, running ahead and scoring quick inside buckets or 3-pointers in the first half.

Duke handcuffed Georgia Tech while hustling on defense in the first half, holding the Jackets to 10 field goals on 27 attempts, tipping rebounds to the right guys and winning the race down the court.

Still Duke found trouble early when freshman forward Kyle Singler picked up two quick fouls, the second was a player-control foul as he made a move for the hoop, in the first 31 seconds of the game.

A few weeks ago, that's a crisis for Duke. Against the Yellow Jackets, sophomore center Brian Zoubek came in and held his own on both ends.

Then, in a planned move, Scheyer, freshman Nolan Smith, freshman Taylor King and junior David McClure joined Zoubek on the court at the 16:14 mark in a rare wholesale substitution.

That group played a good three-minute stretch that saw Duke, which started slow, extend its lead from one to six points.

"We did that at the Maui Invitational where all 10 guys played," King said, "We wanted the same approach here where we're playing everyday."

Krzyzewski, again in a planned move, sent in the same group when Georgia Tech slashed Duke's 50-31 second-half lead at the 18:45 mark to 52-44 with a 13-2 run.

The Jackets' Jeremis Smith, who scored 13 points, and Maurice Miller, who had 16, completed three-point plays and Miller hit a 3 during the run.

Krzyzewski went back to the second unit but admitted after the game, the situation was tougher since Tech had all the momentum.

Tech cut deeper into the lead before Gerald Henderson, Greg Paulus, Lance Thomas, Singler and Nelson came back into the game at the 14:25 mark, and Duke's lead looked pretty slim at 52-48.

Lewis Clinch's jumper cut it to two with 13:38 left in the game, and Duke had to fight out of it.

"We don't think any team can run with us, can keep up with us, as well-conditioned as we have been all season," Georgia Tech's Jeremis Smith said. "We really had them back on their heels, but we let them back in it by fouling."

Singler played just three minutes in the first half while Zoubek had two rebounds, two points and two steals in 11 first-half minutes.

Singler still wasn't taking many shots in the second half, though he'd escaped any further trouble.

So he made his mark by stealing a Georgia Tech inbounds pass two possessions later and feeding Nelson for a quick 3-pointer in the corner to put Duke up 56-50.

That was part of a 12-0 run that put the Devils on safe ground the rest of the way.

The fact that Krzyzewski played 11 players and eight played at least 12 minutes is no small thing.

Krzyzewski rarely has played that many bodies for that many minutes during the postseason in his 28 seasons at Duke.

But this is a different Duke team and, this season, Krzyzewski has been open to a lot of ideas he hasn't always embraced in seasons past -- zone defense, fast-paced offense based on the Phoenix Suns' playbook, etc.

During practice this week, Krzyzewski said he felt it best to use the blue unit together, since the players practice together in game situations. That's why he sent all of them in all at once, with Scheyer leading the group, twice in the game.

"They all had a good week of practice," Krzyzewski said. "It's spring break so I worked them harder. I'm trying to think ahead when it's not spring break. They had all worked so hard and the way to show you have confidence in them is to play them."

(Staff writer Robbi Pickeral contributed to this report.)