Akeem Richmond scored 17 points to lead East Carolina (6-2), an instate program making its first trip to Chapel Hill. The Pirates kept cutting into UNC's lead and got as close as four points in the final minute, though they couldn't overtake the Tar Heels on their home court.
The Pirates outscored the Tar Heels 61-51 after halftime.
Lebo played for Dean Smith and then-assistant Roy Williams at UNC from 1985-89, and even played in the first game in the Smith Center as a freshman in January 1986.
He had coached against his alma mater once before, losing 85-59 here while at Tennessee Tech during the 1999-2000 season. The Pirates made this one much closer after a slow start with a tenacious performance.
After trailing 42-26 at the break, East Carolina played more aggressively and got into the double-bonus at the foul line by midway through the second half. The Pirates kept trading baskets with the Tar Heels down the stretch and inching closer before Richmond knocked down a pair of 3-pointers in the final minute, the second bringing East Carolina within 89-85 with 26.6 seconds left.
Dexter Strickland answered with a pair of free throws to push the lead back to six. Then, after East Carolina's Marshall Guilmette's layup, Leslie McDonald had a slam with 10.5 seconds left that ultimately sealed the victory.
Still, there was plenty for Williams to feel frustrated about in this one - and some of that showed midway through the second half.
Less than a minute after the Pirates had pulled to within 47-40 with 14:26 left, Williams - who typically hoards his timeouts - burned one and spent the entire stoppage screaming at his flat team from one knee.
His team eventually responded with a burst, running off a 7-0 run to rebuild some cushion and later take a 71-53 lead on Reggie Bullock's layup with 7:16 left. But the Pirates didn't go away.
East Carolina shot 53 percent in the second half, including 6-for-13 from 3-point range.
There was a moment of silence before the game due to Friday's school shooting in Newtown, Conn.