P.J. Hairston added 18 for the Tar Heels (8-2), who emerged from a weeklong break due to fall exams with their third straight victory. North Carolina shot 55 percent in the first half to build a 16-point lead at the break, but the Pirates coached by former UNC guard Jeff Lebo outplayed the Tar Heels throughout the second half and made it a tough run to the finish.
East Carolina scored 61 points in the second half and got as close as four twice in the final 30 seconds.
"Right now, there's not anything ol' Roy's ecstatic about, let's put it that way," the Hall of Fame coach said.
There were plenty of reasons why.
None of his big men managed an offensive rebound, prompting Williams at one point to play five guards. His team didn't switch on screens after being told to do exactly that during a timeout and promptly gave up a layup. The Tar Heels left ECU's Akeem Richmond open repeatedly in the second half along the perimeter.
Williams, who typically hoards his timeouts, unleashed some of his frustration when he burned one midway through the second half and spent the entire stoppage screaming from one knee at his flat team.
His team responded with a surge that pushed the lead to 18 with 7 minutes, 19 seconds left but didn't sustain that momentum and let the Pirates right back in it.
"It just seemed like they had more energy than we did," senior guard Dexter Strickland said. "We're not going to win too many games if we continue to play like that."