DURHAM — The party, unexpectedly delayed for a prolonged period, was back on. Duke expected a win Wednesday night, and the Blue Devils would deliver. Just not right away.

North Carolina held off the celebration as long as the Tar Heels could, probably longer than anyone could have expected. In the end, they could slow, but not stop, Duke’s offense, and their own failings at the free-throw line didn’t help, either – especially as the Blue Devils made 13 straight to ice the 73-68 win.

Yet amid all the celebration, it hadn’t been long since Cameron was beset with worry instead.

Early in the second half, after an unusually ineffective Mason Plumlee picked up his third foul and as North Carolina continued to get to the rim seemingly at will – James Michael McAdoo epitomizing the trend with an overhead, reverse lay-in – what had once been happy laughter in the bleachers was replaced by nervous, restless murmuring. The bench wasn’t far behind.

“If anything, there was so much anticipation, we got a little anxious at that point,” Plumlee said.

This wasn’t what anyone bought tickets – or camped out in the rain – to see. The Duke fans were expecting a typical game between a ranked Duke team and an unranked North Carolina team in Cameron, most of which have been decided by double-digit margins – an average of 18 points going back two decades.

Perhaps because of that history, and with Mike Krzyzewski celebrating his 66th birthday, there was really none of the nervous tension and excitement that typically characterizes this game. It was more of a valedictory feel, from the birthday hats to the signs mocking everything from North Carolina’s academic scandal – “Go To Class Carolina” – and the Tar Heels’ possible, if unlikely, future in the NIT.

It felt more like college basketball’s most festive party than college basketball’s most fervent rivalry, at least until North Carolina came out like the records didn’t matter, which is what everyone always says about this game even if history would indicate it rarely turns out that way.

Into that environment, Roy Williams sent an unexpectedly small lineup, and his team brought an uncharacteristically tenacious defensive effort that caused considerable disruption to the Duke offense. The Blue Devils didn’t record an assist until late in the first half, and even P.J. Hairston, the Tar Heels’ weak link without the ball to this point, was a determined defender.

That was enough to give the Tar Heels the lead until midway through the second half, when the Blue Devils started hitting shots and never looked back. Duke had made only two 3-pointers in the entire game when Seth Curry, Rasheed Sulaimon and Tyler Thornton made three in a row before Plumlee got into the act, backing down McAdoo for an easy bucket and a five-point lead.

It stayed like that for more than four minutes, as if both teams wilted once Duke finally took the lead just about everyone expected them to have much, much earlier. And North Carolina, which was within four with 74 seconds to play, left its best chance to win at the free-throw line, missing six straight in the second half and going 13-for-23 for the game.

“I’m not into moral victories, and I told them that in the locker room,” Williams said. “But I am pleased with the effort they gave and the focus they showed.”

That was as close as the Tar Heels would come to putting a damper on a celebration that would not be deferred, Krzyzewski applauding the fans in their hats as he walked off the floor, the party in full swing.

DeCock: ldecock@newsobserver.com, @LukeDeCock, (919) 829-8947