Nelson scored 19 points in the second half to finish with a season-high 24 points and put Alabama ahead before blocking RJ Davis' tying layup attempt. Rylan Griffen scored 19 points, tying his career high with five 3-pointers, and Aaron Estrada also scored 19 points for the fourth-seeded Crimson Tide.
The Tide will face sixth-seeded Clemson on Saturday for a berth in the Final Four. The Tigers defeated second-place Arizona 77-72 on Thursday.
After Nelson blocked Davis' shot with 25 seconds left, Davis dribbled furiously before missing a layup and the Tar Heels were called for a shot clock violation with eight seconds remaining. They had to foul and send Nelson to the line. He calmly scored both to take the lead 89-85.
Armando Bacot scored inside with one second left to put North Carolina behind 89-87. The Tar Heels fouled Nelson again with 0.9 seconds left. He missed both, and the blueblood Tar Heels, who had six national championships, ran out of time.
Bacot finished his last game for UNC with 19 points and 12 rebounds. Cormac Ryan had 17 points and 5 three-pointers, and Davis had 16 points.
At times, UNC coach Hubert Davis looked like he was playing for his alma mater, where he starred under Hall of Famer Dean Smith from 1988-92. Davis was running up and down the sideline in his white sneakers, gesticulating, yelling and putting on and taking off his glasses as he experienced every play of his team.
The Tide made its other Elite Eight appearance in 2004, losing to UConn under coach Mark Gottfried. Alabama, known for its football program, has never made it to the Final Four.
UConn, the other No. 1 seed competing on Thursday, easily beat San Diego State 82-52 as they continue their quest to win back-to-back championships.
