DURHAM, N.C. – The formula is easy to understand for No. 4 Duke. When the 3-pointers are falling, the Blue Devils can be tough to handle.
And when they're off — as they were for too long against rival North Carolina — they get beat.
The sixth-ranked Tar Heels routed the Blue Devils 88-70 on Saturday night to claim a second straight Atlantic Coast Conference regular-season title and the top seed in next week's league tournament.
Perimeter-reliant Duke, which hit 14 3-pointers in winning the first meeting last month, failed to hit even half that many in the rematch, and that meant big trouble against the bigger, stronger Tar Heels.
The Blue Devils finished 6 of 21 from 3-point range. They missed 15 consecutive shots, including their first seven 3s, and had two 7-minute field goal droughts in the opening half.
"When you base, like we do, a lot of our offense on 3-point shooting ... some will say, 'Don't.' That's who we are, man," Duke coach Mike Krzyzewski said. "And if we're not hitting them, we have a much greater chance to lose."
Mason Plumlee scored 17 points, and brother Miles Plumlee added 16 points and 11 rebounds in his final home game for the Blue Devils (26-5, 13-3). Freshman guard Austin Rivers — the hero of the last meeting between the teams — had 15 points.
But Duke — which erased a 10-point deficit in the final 2½ minutes to win the first matchup, then rallied from 20 down in the second half to beat North Carolina State — couldn't come up with another improbable escape and instead had its seven-game winning streak snapped.
"Throughout the year, we've been immature. We always want to see how little we have to do to win," Miles Plumlee said. "You give a team like that a 20-point lead, it's nearly impossible to win. We need to fight, like we did at times, for a whole game."
For too long in this one, the shots didn't fall for the Blue Devils, and that left them down 48-24 at the break — their largest halftime deficit ever at Cameron Indoor Stadium and their deepest anywhere since the 1990 team trailed the Tar Heels by 24 in Chapel Hill.
The closest they got in the second half was 75-64 on Miles Plumlee's free throw with 6:01 left. But Seth Curry missed an open 3-pointer roughly 30 seconds later that would have brought down the house.
Instead, Kendall Marshall hit a 19-footer with 4 minutes left, James Michael McAdoo added a layup and Harrison Barnes swished a deep 3 to stretch it to 82-64 with 2 minutes to play.
Marshall finished with 20 points and 10 assists for the Tar Heels (27-4, 14-2). Tyler Zeller had 19 points and 10 rebounds, and Barnes added 16 points.
"My team's had some bounce-back to them all year long," North Carolina coach Roy Williams said. "We go down to Florida State and lose by 3 million and everybody's jumping off the bandwagon ... but our team kept playing. We lose to Duke and everybody's got a great opinion of how stupid we are ... (and) my team kept playing."
North Carolina shot 54.5 percent, built a 45-28 rebounding advantage and won its seventh straight since last month's loss to the Blue Devils.
For Zeller, it was a welcome catharsis after his late-game struggles in the previous meeting. Back then, he accidentally batted a ball into the Duke basket and missed two free throws in the final minute before Rivers hit that last 3 over him.
Those noisy Cameron Crazies persistently reminded him of it, chanting "Tyler Zeller, MVP" at him during pregame warmups.
"Yeah, I heard it all," Zeller said.
And the North Carolina big man got the last laugh, making his final trip to Cameron one to remember by hitting nine of his 11 shots before fouling out in the final minute. Only when he and John Henson got in foul trouble did the Tar Heels' offense really bog down.
Henson had 13 points and 10 rebounds, giving the Tar Heels three players with double-doubles — the first time they've done that since 2003 — while Reggie Bullock added 12 points.
Curry finished with 12 points on 3-of-13 shooting for Duke.
Among the famous faces in the crowd were NFL players Peyton Manning — who has been throwing on campus under the tutelage of his college offensive coordinator, Duke coach David Cutcliffe. Manning sat next to Cutcliffe in a courtside seat under the basket the Blue Devils defended in the first half.
Those two saw plenty of early action — all by the Tar Heels.
North Carolina once again raced out to a quick double-figure lead, this time riding an 18-1 run in which it converted nearly every shot it took in the paint. That lead grew throughout the half, with Marshall's jumper with 3 seconds left stretching it to 48-24 at the break.
"We were just kind of overwhelmed, by them and the situation," Krzyzewski said. "It's like a surprise gift, you know? You open it up, and for the most part, it's been a nice surprise. I never have any idea of what's inside the present. And today there was nothing. It was an empty box."