Jahlil Okafor showed off all the moves - a spin, a dribble drive, a short jumper - that have made Duke's freshman big man possibly the nation's top player.

When he's playing like that, the Blue Devils have a shot to finish as the nation's best team right alongside him.

Okafor scored 18 of his 26 points in a dominating first half and top-seeded Duke beat San Diego State, 68-49, in Charlotte, N.C., on Sunday in the NCAA tournament, sending the freshmen-led Blue Devils back to the Sweet 16 to continue their push for coach Mike Krzyzewski's fifth national title.

"It would mean the world to me," Okafor said. "I've always wanted to win a national title. ... That's what [the freshmen] came to Duke to have an opportunity to win a national title. That is where all of my focus has been this season and that is what it is still is."

Duke - holding a No. 1 seed for the 11th time in 18 seasons but its first since 2011 - advanced to face fifth-seeded Utah in Houston's South Regional semifinals. The Blue Devils (31-4) reached the Sweet 16 for the 22d time under Coach K, who said this group featuring four freshmen among its eight scholarship players is still improving.

"They're together," Krzyzewski said. "We have talent, we're getting older by experience, and so we just - we got better here these two games."

Fellow freshman Justise Winslow added 13 points and 12 rebounds for Duke, which shot 55 percent against the eighth-seeded Aztecs (27-9) two days after shooting 63 percent against 16th-seeded Robert Morris.

Okafor scored 21 on 9-for-11 shooting against the seriously undersized Colonials, then made 12 of 16 shots against the Aztecs - who had size to wrestle with him but no way to stop him.

Winslow put on his own show with five assists, four steals and three blocks, one a jaw-dropper on JJ O'Brien at the rim.

The Aztecs were trying to reach the Sweet 16 for the third time under Fisher, but San Diego State - with a few players and coaches battling a stomach ailment - got off to a bad start and struggled to slow Duke early.

Gonzaga 87, Iowa 68 - Kyle Wiltjer scored 13 of his 24 points during Gonzaga's flawless first half, Domantas Sabonis added 18 points and the second-seeded Bulldogs advanced to the round of 16 for the first time since 2009 after rolling over No. 7 seed Iowa in the other South Regional matchup in Seattle.

After five straight departures on the first weekend, the Bulldogs (34-2) are back in the regional semifinals, thanks to efficient offensive performance in the first 20 minutes that Iowa could never overcome.

Wiltjer made his first six shots before finally missing a three-point attempt midway through the second half. Sabonis added eight in the first half, including a thundering left-handed dunk that was followed by a scream that had KeyArena roaring just like Gonzaga's home gym.

Jared Uthoff led Iowa (22-12) with 20 and Aaron White added 19.

Wiltjer was nearly perfect. He made 10 of 12 shots and 4 of 6 three-pointers. His 24 points came in just 25 minutes as he was slowed by early foul trouble. Kevin Pangos added 16 points.