Marcus Paige made two free throws with 3.9 seconds left to help No. 19
Paige also made a huge shot to beat the clock in the final minute, helping the fifth-seeded Tar Heels (24-10) hold off the tournament's top seed and reigning champion in a tense finish.
Freshman Justin Jackson scored a season-high 22 points to lead the Tar Heels, who never trailed and led by as many as 13 points before all-ACC guard Malcolm Brogdon single-handedly brought the Cavaliers (29-3) back.
North Carolina will face the Duke-Notre Dame winner in the finals.
Aaron Harrison and Karl-Anthony Towns each scored 13 points and No. 1
Wayne Selden Jr. scored 20 points and ninth-ranked
Sam Dekker scored 17 points, Frank Kaminsky added 16 points and 12 rebounds and No. 6
Nic Moore scored 20 points to help No. 20 Southern Methodist defeat East Carolina, 74-68, in the American Athletic Conference quarterfinals. Markus Kennedy added 15 points and six rebounds for the top-seeded