CHAPEL HILL, N.C.During Wednesday’s entire first half in Chapel Hill, the Duke Blue Devils scored only six points inside the paint, all on second-chance putbacks, none off of set plays. So it was appropriate and certainly not surprising when, with just seven minutes remaining in the tied game, freshman Mason Plumlee locked up a rebound, stepped, and dunked the ball behind his head after yet another Kyle Singler miss from the floor.

Before that dunk, the Devils and the UNC Tar Heels had traded the lead 11 times in a game that seemed more about withstanding errors like missed free throws and bad passes than actual execution. But after that slam, it was all Duke in a tenacious, low-scoring 64-54 win, winning for only the third time in the last 10 meetings of the legendary rivalry.

‘Mason’s play on that offensive rebound reverse dunk was hugenot just for the two points,” said Duke coach Mike Krzyzewski after the game, noting that it did break the tie. ‘But for his teammates to see the ball go in with that force.”

Indeed, there hadn’t been many power moves in the contest until the younger Plumlee’s playoffensively, at least. Duke, which hasn’t bet its spoils on the three this year, shot a dozen of them in the first half alone, connecting on six split evenly between Jon Scheyer and Kyle Singler. Otherwise, they went just three for 28 from the field, with Nolan Smith missing all of his seven attempts. Such poor Duke shooting22.5 percent in the first half, their lowest in any period this seasonkept Carolina close. The Heels shot eight for 24 inside the arc, alongside consecutive three-pointers from junior guard Will Graves. Carolina’s interior defense was sterling, too, leading to 15 blocks (with six by Ed Davis, who scored only four points and missed critical shots from the charity stripe down the stretch) during the course of the game and a number of redirected Devil attempts.

‘We block shots, but not like they do,” said Krzyzewski. ‘I thought their defense was so good, but sometimes when you’re playing that hard, you put the pressure on the first shot, and then we got the second shot. If we knock it backed out, we usually got something better than if we went righ back at ’em.”

During the first half, for instance, each team had a rebound for nearly every point, but Duke’s work on the offensive boards supplied a critical advantage. Two offensive boards early in the first half yielded second-chance three pointers for Duke, and a series of three consecutive misses by Jon Scheyer led to an eventual goal by Mason Plumlee that drove Duke’s one-point half-time advantage. In the end, Duke outrebounded UNC by nine, outscored them by 10.

By the time of Plumlee’s dunk, Duke had actually figured out how to score against the Tar Heels defense without three pointers. Smith finished the game with 10 points, netting all of them in the second half after hitting a floating jumper just inside the arc. He followed it less than a minute later with another. Those late points gave Duke the slicing push to the inside it lacked for the first half

‘No moral victories, guys. It’s not that,” said UNC coach Roy Williams. His team scored less points Wednesday night than it has all year and less than any of his squads have scored during his UNC tenure. ‘We’ve got to play better. I thought we really had the intensity during the first 30 minutes that we needed and should have had for the whole season.”

The win could be a costly one for the Devils: Senior Lance Thomas, whose length and quick feet have made him Duke’s most versatile defender and one of the best in the country, headed to the locker room with a knee injury with more than 17 minutes remaining in the game. He never returned to the bench. Krzyzewski said it didn’t appear to be a torn ACL, but the injury isn’t minor, either.

‘We’re concerned about Lance,” said Krzyzewski. ‘He’s been our emotional leader and our best defender inside.”

That might force the issue of Mason Plumlee, whose game, though still coltish, has improved sporadically but convincingly this year. Tonight, in 27 minutes, he led the team with nine rebounds, and his flashy passes offer Duke’s interior a tool it’s long lacked. Krzyzewski acknowledged the critical role he and freshman Andre Dawkins, who provided scoreless but significant minutes tonight, will play, especially in the event of a prolonged Thomas absence. Dawkins was part of that crucial five-minute stretch late in the second half in which Duke reversed the Tar Heels’ four-point lead and pushed it to six in their favor.

‘He didn’t score, but he got a rebound and he played very good defensive,” Krzyzewski said of Dawkins’ help. ‘If Lance is out, that’s probably one of the looks we’ll have, with Kyle playing at the four.”

Ultimately, however, it’s UNC that’s on the ropes. This loss pushes them to a 13-11 record on the season, with four more ACC road games scheduled in the next month. And Saturday, they’ll host N.C. State at home, just two weeks after the Wolfpack led the Tar Heels in the second half before going disastrously cold. It’s now become less a question of an invitation to the NCAA tournament and one of ending the season with a winning record. For Williams, though, it’s only about turning the Tar Heelswho’ve now lost four in a row and eight of their 10 games in 2010around by Saturday.

Asked where his team was headed next, Williams jokes his way around the question. ‘Upstairs,” he said to media room chuckles. ‘Get the tape and go home and watch the daggum tape and come to practice tomorrow and see if we can get better.”

Pressed, Williams’ answer was simply a more solemn, frustrated version of the same storyimproving his team in the time they have left: ‘It makes no difference. We gotta play. You can be 2-7 or 70-2. We gotta freakin’ practice. We gotta practice. We gotta game we gotta play.”