ST. LOUIS — Oregon forward Maarty Leunen seems to have figured out how to tell whether freshman Tajuan Porter is going to have a big night.

"We call it the 'heat check,' " Leunen said. "He'll shoot one more just to see if it goes in. Then he's on fire and we just keep giving it to him."

Porter, the 5-foot-6 freshman that no other big school wanted, tied an NCAA regional record with eight 3-pointers and finished with 33 points, as Oregon withstood a frantic comeback to beat seventh-seeded UNLV 76-72 yesterday in the Midwest Regional.

The third-seeded Ducks advanced to play top-seeded Florida tomorrow.

"You get the feeling he was feeling good," Ducks guard Aaron Brooks said. "He's been doing it all year. It's not surprising to me. I had a front-row seat, the best seat in the house."

The Ducks wouldn't be on the precipice of their first Final Four since winning it all in 1939 without the diminutive guard, who hit four 3-pointers against Winthrop in the second round to send Oregon to the second week of the tournament.

That he's playing at this level at all is an upset of sorts.

The Oregon coaching staff went to Renaissance High School in Detroit to scout guard Malik Hairston, a McDonald's All-American. But an assistant coach spotted Porter — two years younger than Hairston — draining shots from all over the court. He implored Kent to give him a chance.

Porter jumped on the scholarship offer from Oregon — the only big-name school to come calling. Now he's become the darling of a tournament lacking a true underdog.

After scoring only eight against Miami (Ohio) in the first round of the NCAA tournament, the "heat check" has only come back positive.

"He had a game of 10 3s and I took him out," Oregon coach Ernie Kent said. "We've seen him play like that before. Nothing really goes through your mind. He's just a terrific player. We thought he was going to be a special, unique player at this level and he sure has been."

Hairston had 14 points and 11 rebounds for Oregon (29-7). Leunen hit three 3-pointers and added 11 points.

"I just came out with a lot of confidence," Porter said.

After he and Hairston hit back-to-back 3-pointers to make it 66-49 with 5:23 to play, UNLV began chipping away.

Kevin Kruger and Michael Umeh combined for 13 points during a 17-4 run that got the Runnin' Rebels within 70-66 with 50.2 seconds to play. But Porter hit 4 of 6 from the line in the last 41 seconds and UNLV's Joe Darger missed a 3-pointer with 30 seconds to go.

"I think it got away from us a little bit," Kent said. "We talked about it in the locker room and you cannot be satisfied with it."

FLORIDA 65, BUTLER 57

ST. LOUIS — Al Horford and Joakim Noah had small spots of blood speckled across their shirts and shorts — remnants of Butler's aggressive, physical play.

For Florida's big men, the red dots were a reminder of how tough it can be to try to repeat as national champions.

"We're going to do whatever it takes," Horford said.

They might have to, because if the top-seeded Gators are going to win consecutive NCAA titles, it seems they're going to do it the hard way.

Horford had 16 points, seven rebounds and a key block in the final minute to help the top-seeded Gators overcome another slow start and hold off undersized Butler 65-57 yesterday.

Florida (32-5), trying to become the first team since Duke in 1992 to win consecutive national titles, advanced to the Midwest Regional final tomorrow against Oregon.

"Teams are going to play you a lot different when you're the defending national champions, and we're aware of that," Horford said.

The Gators trailed by as many as nine points and never found their comfort zone against the scrappy Bulldogs (29-7).

But they took control in the final two minutes — thanks mostly to Horford. The 6-foot-10 forward converted a three-point play with 2:34 remaining, then blocked a shot with 16.3 seconds to play.

Noah and Horford — 3 inches taller than any of their opponents — made the most of their size advantage. They drew fouls and went a combined 17 of 21 from the line. They also had five blocks.

"We couldn't do it without fouling, and that's what got us," Butler coach Todd Lickliter said.