Providence's Bryce Cotton scored a career-high 36 points and made one dazzling shot after another down the stretch. But he also fumbled a long rebound in the final moments, robbing the Friars of a chance for a last-second miracle.
Had North Carolina (24-9) lost, it would've been the first time since 1979 the Tar Heels and rival Duke lost on the same day of the tournament.
The Blue Devils fell earlier to 14th-seeded Mercer, and the Friars nearly handed North Carolina a similar stunner.
Marcus Paige led North Carolina with 19 points.
North Carolina tipped off loathe to wind up as another NCAA blue blood sent packing by a smaller school reveling in a rare tournament berth.
Tar Heels fans didn't seem worried: when Duke's 78-71 loss flashed on the scoreboard, a burst of applause erupted.
But they'd wind up squirming in their seats worried about suffering a similar fate.
The Friars, who haven't won in the tournament since 1997, squeezed everything out of their six-man rotation to give talent-rich North Carolina all it could handle. Each time the Tar Heels flexed their unmatchable athleticism — forward J.P. Tokoto's spinning dunk after swiping a midcourt pass got everyone gasping — Providence answered.
Cotton made sure of it.
Saving the performance of his career for his final game at Providence, Cotton was 13 of 23 from the floor and had eight assists. But there was nothing on his face but anguish after corralling a missed McAdoo free throw with less than 2 seconds left, only to bumble the ball off his knee and out of bounds.
McAdoo finished with 16 points and 10 rebounds and Brice Johnson also scored 16 for the Tar Heels.
Ladontae Henton was Cotton's sidekick, finishing with 16 points and 11 rebounds. Tyler Harris added 13 for the Friars (23-12), who were a bubble team before winning the Big East tournament.
Providence trailed just 39-36 at halftime, and with 10 minutes left, a nifty one-handed turnaround by Cotton pulled the Friars within a basket. The senior never came out for a breather, playing every possible minute for the 16th time in 19 games.
Two possessions later, Providence's ironman struck again — this time to put the Friars up 60-58, their first lead since halftime.
Cotton — the smallest guy on the floor at 6-1 — made a 3-pointer to push Providence's lead and then roared at midcourt, while North Carolina trudged back to the bench looking baffled.
But Paige brought the Tar Heels back, hitting a 3-pointer with 1:06 left to tie the game at 77.
San Antonio has been a booby trap for some of North Carolina's best squads. Future NBA stars Antwan Jamison and Vince Carter lost here in the 1998 Final Four, a heartbreak that Tyler Hansbrough would come to know in the Alamodome a decade later. This time, San Antonio is the starting point for a North Carolina team that has been inconsistent.
Star guard P.J. Hairston never played because of NCAA violations, and Leslie McDonald was suspended for nine games. And an academic fraud scandal has continued to embarrass the athletic department.
Coach Roy Williams said it had been “a tough time around Chapel Hill.”
Not pulling this one out would've made it tougher: North Carolina hasn't lost in the first round since 1999.