GREENSBORO, N.C. (AP) -- Only a week ago, No. 15 North Carolina was rolling along with a long winning streak that had the Tar Heels playing with confidence.
Things suddenly look very different.
The Tar Heels trailed by 20 points before making a late comeback in Friday's 80-75 loss to Pittsburgh in the Atlantic Coast Conference tournament. Now they're headed into the NCAA tournament with two straight losses, the first time for the program since coach Roy Williams' first season in 2003-04.
North Carolina had won 12 straight games to dig out from an 0-3 ACC start, including a win against Pittsburgh, before losing last weekend at Duke in the regular-season finale.
"I think in the wins we had, we really set the tone defensively," sophomore Marcus Paige said. "We were really active. We were all over the place in the defensive ends. That hasn't happened recently. ... We need to start doing that again if we want to be successful."
The most glaring problem in each loss was UNC's poor play on the boards. The Tar Heels managed just 20 rebounds at Duke, their lowest total in 27 years, then couldn't keep Pitt's Talib Zanna off the boards in Greensboro.
Zanna had 19 points and a career-high 21 rebounds in the quarterfinal win.
James Robinson also scored a career-best 19 points for the fifth-seeded Panthers (25-8), who used a dominating start to build a huge lead before having to hold off a late rally by the fourth-seeded Tar Heels (23-9).
Pittsburgh led by 20 points with 7:22 left before UNC's frantic comeback behind Paige, who scored 20 of his 27 points after halftime before fouling out with 25.4 seconds left.
UNC got it to 78-75 on Nate Britt's jumper with 11.4 seconds left but couldn't complete the comeback. James Robinson knocked down two free throws to make it a two-possession game again right after Britt's score, then Lamar Patterson rebounded a hurried 3-pointer by James Michael McAdoo with 4.3 seconds left to essentially seal it.
Now, after a dominating performance in Thursday's second round and a bumbling-but-successful finish Friday, the Panthers will face sixth-ranked and top-seeded Virginia in Saturday's semifinals.
Zanna, a 6-foot-9 fifth-year senior, came within two rebounds of tying the single-game tournament rebounding record that had stood since 1959. He fouled out with 1:03 left.
Zanna had 10 offensive rebounds -- one shy of UNC's team total -- and helped Pitt control the boards while taking a 21-6 edge in second-chance points against a team that was third in the league in rebounding margin for the regular season.
With all those point-blank extra looks off offensive rebounds, Pitt shot 52 percent for the game.
North Carolina spent all day trying to recover from a terrible start. It missed 16 of 19 shots and fell behind 25-8, though its late comeback at least gave them some hope of sticking around Greensboro a little longer.
North Carolina shot 42 percent, though much of that production came after Pitt had built a 61-41 lead on Josh Newkirk's three-point play midway through the second half.
The Panthers have won five of six to pull out of a three-game losing streak that started to threaten their NCAA tournament chances, with this ranking as probably their best of the year.
Follow Aaron Beard on Twitter at http://www.twitter.com/aaronbeardap