For the past four days of the NCAA tournament, the four top seeds had avoided early trouble, letting No. 2 seeds Duke and Missouri take all the attention by falling out. That all changed around 8 p.m. Sunday night when word came that North Carolina point guard Kendall Marshall had broken his right wrist.

The Tar Heels cruised past Creighton 87-73 Sunday evening, joining fellow No. 1 seeds Michigan State, Kentucky and Syracuse in the Sweet 16, but now face major concerns over their playmaker and floor leader.

The school announced Marshall fractured his scaphoid bone after going hard to the floor following a drive to the basket and foul with 10:56 left in the second half Sunday night. Marshall played an additional three minutes on adrenaline before taking the bench. X-rays revealed the fracture.

“He has a fracture of the scaphoid bone in the right wrist,” North Carolina coach Roy Williams told CBS in a hastily-organized interview. “There’s nothing else that we can say because we’ve got to see a doctor and talk to the family. There will be no update tonight. We just don’t know…He’s just a wonderful, wonderful kid and you hate that to happen.”

Marshall shoots left-handed, which is one reason he had for encouragement. If it was my left hand, then we'd probably have some problems. But we'll take it day by day and figure it out."

On the very day ACC defensive player of the year John Henson returned after missing three games with a sprained wrist, giving the Tar Heels a big emotional lift and a double-double, came another tough blow to the second overall seed in the tournament.

As formidable as the Tar Heels’ front line is with Henson and ACC player of the year Tyler Zeller, it’s the sophomore Marshall who makes their offense go. He set the ACC single-season record for assists this year, now with 351, and averages 9.8 per game.

With Dexter Strickland already out for the season with a torn knee ligament, North Carolina’s backup point guard options are limited. Freshman Stilman White has averaged only four minutes per game. The Tar Heels could turn to Justin Watts or P.J. Hairston for some ball handling, but neither is a true point guard.

North Carolina would play again Friday in St. Louis against No. 13 seed Ohio. Another silver lining for the Tar Heels is that the Midwest region has lost its No. 3 seed Georgetown and No. 4 seed Michigan. Both Ohio and N.C. State are into the Sweet 16 as double-digit seeds.

Ohio topped South Florida 62-56 Sunday to become only the fifth No. 13 seed to ever make the Sweet 16, joining Bradley (2006), Oklahoma (1999), Valparaiso (1998) and Richmond (1988).

Both No. 15 seeds Lehigh and Norfolk State wound up won and done for this tournament, after scintillating upsets over Duke and Missouri respectively. Only six No. 15 seeds have ever defeated a No. 2 seed, but none have advanced to the Sweet 16.

Florida overwhelmed tournament darling Norfolk State Sunday with 25 unanswered points and seven 3-pointers in the first half, prompting an almost apologetic-sounding Coach Billy Donovan in his halftime interview.

“In this tournament, one day to the next is always different,” Donovan said.

Lehigh, which upset Duke on Friday, succumbed to Xavier 70-58.

One of the original Cinderellas, N.C. State, knows a thing or two about making improbable NCAA tournament runs.

The very last team to hear its name on selection Sunday, and the fifth team in from the ACC, just willed its way into the Sweet 16 with a 66-63 win over No. 3 Georgetown.

Seeded No. 11,  North Carolina State advanced to the Sweet 16 for only the second time since the late Jim Valvano’s final season there in 1989 and the fifth time since its shocking run to the 1983 national championship.

“You never know what to expect in this tournament," said N.C. State sophomore Lorenzo Brown of Roswell, who scored seven of his 12 points in the final 2 ½ minutes. “A lot of great teams went down a couple of days ago. And we're just out here playing our best. And Coach is a believer in us and we believe in ourselves.”

In a throwback matchup, the Wolfpack defeated the storied Hoyas, with their tradition of players like Patrick Ewing and Alonzo Mourning, with a “Zo” of their own. Lorenzo Brown hit a tough baseline floater to build a seven-point lead with 2:27 to go, made five of seven free throws from there and got just enough of a hand in Jason Clark’s face at the buzzer to force an errant 3-pointer.

Brown, and N.C. State’s athletic front line of C.J. Leslie and Richard Howell have seen their confidence snowball since a semifinal run in the ACC tournament. First-year coach Mark Gottfried gave some insight why in an impassioned pre-game speech to his team Sunday, which CBS aired.

“I believe with all my heart, you’re good enough,” Gottfried told his team. “You’re good enough to advance. There’s a plane waiting for you to take you to St. Louis. There’re hotel rooms waiting for you. There’s a game waiting for you to be played in St. Louis, huh?”

The Wolfpack answered by rallying from 10 points down to take a 3-point halftime lead. They rendered Georgetown’s key player Henry Sims moot, by keeping him foul trouble throughout. Sims didn’t make his first field goal until 49 seconds remained.

The Associated Press contributed information to this article.