COLUMBIA, S.C. --
Zion Williamson took on 7-foot-6 Tacko Fall all game long but in the end, it was top-seeded Duke which prevailed when two last-second shots by No. 9 UCF rolled off the rim.
Aubrey Dawkins finished with 32 points, but his tip-in try just missed and Duke advanced with a 77-76 victory to reach the Sweet 16.
Williamson had 32 points, including a layup over Fall with 14.4 seconds left and his team trailing 76-73. Fall fouled out on the play and the 6-foot-7 Williamson missed the free throw, but fellow freshman RJ Barrett scored on a putback to put the Blue Devils (31-5) ahead.
UCF (24-9) had a final chance. Two of them, actually, from in close.
B.J. Taylor missed a short jumper and Dawkins' tip attempt with less than 2 seconds left, spun off the rim. Duke got the rebound, ran out the clock and moved on to the Sweet 16 for the 27th time and fourth time in the past five years.
Dawkins cringed at the miss. His father, Johnny, is the UCF coach and was a former Duke star and longtime assistant under coach Mike Krzyzewski. The two coaches shared a long embrace at midcourt after it was over.
It looked as if Dawkins might take down his dad's alma mater in the NCAAs.
His last basket broke a 70-all tie and when Fall dunked Taylor's miss -- the play was reviewed for a possible shot-clock violation -- the Knights were ahead 74-70.
Cam Reddish came back with a 3-pointer for Duke but Taylor made it 76-73 with two foul shots with 45 seconds to go.
Williamson then missed a 3, but Duke grabbed the rebound and got the ball back to their dominant freshman. He caught a pass left of the key and dribbled straight into Fall's 7-6, 310-pound frame.
Fall had stuffed Williamson three previous times and Duke's young star was less effective underneath than he'd been his past four games. But Williamson got this shot to drop.
Williamson, a national player of the year candidate, was c affected by Fall as the Knights' senior stood 11 inches taller than Williamson and has a wingspan of 8-foot-4.
But with Fall inside, Williamson went outside hitting three 3-pointers after entering with just 18 on the season. And when Fall was hit with foul trouble, Williamson charged to the hoop. Fall finished with 15 points and six rebounds in his final college game.
Duke's four freshmen combined for 72 of its 77 points. Reddish had 13 points and Tre Jones 11.
It was the second-straight sluggish start for Duke in the NCAA Tournament. But the Blue Devils closed the first half with a 12-2 run to move in front.
Trailing 34-32 in the final four minutes of the opening half, Williamson hit a short jumper, then collected Jordan Goldwire's miss for a three-point play. Barrett added a three-point play and Williamson threw a one-handed bounce pass to a streaking Jones for an easy layup as Duke led 44-36 at the break.