GAINESVILLE, Fla. (AP) -- Wes Byrum started celebrating before his kick even cleared the uprights. He knew it was good when it left his foot.
For Auburn, it was actually perfect. For Florida, it was a kick where it hurt most.
Byrum's 43-yard field goal as time expired lifted the Tigers to a 20-17 victory over No. 4 Florida on Saturday night and gave them one of the biggest upsets on a day filled with them.
"It doesn't get any better than that," said Byrum.
The loss snapped an 11-game winning streak for the defending national champions, who lost to Auburn last year, and gave the Gators their first home loss under coach Urban Meyer. They had won 18 in a row, 17 straight since Meyer took over in 2005.
It also might have jeopardized Florida's chances of repeating. Then again, with all the other upsets Saturday, the Gators surely won't slip too far out of the picture.
Florida (4-1, 2-1 Southeastern Conference) could take a big step back next week at No. 2 LSU. Then again, if the Gators perform like they did Saturday, they could be in for another long day.
Auburn has won only four times in the last 12 meetings with Florida but all four wins were when the Gators were highly ranked. Before Saturday's 20-17 victory, Auburn's last win in Gainesville was in 1994, an upset win over No. 1 Florida.
Auburn (3-2, 1-1) played sound defense, prevented Tim Tebow & Co. from making many big plays and took advantage of several mistakes to build a 14-0 lead at halftime.
A running-into-the-punter penalty kept Auburn's opening drive alive. It ended with Kodi Burns' 6-yard touchdown run. The Tigers made it a two-touchdown game with Ben Tate's 3-yard run that followed a blocked field goal.
It was 17-3 before Florida evened the game with two fourth-quarter touchdowns.
However, Auburn came up big in the closing minutes. Byrum attempted the winning kick, just as Meyer called timeout. The kick was true, but Byrum had to do it again.
He did, and it was right down the middle.
"I was pretty excited," said Byrum, who missed his only attempt last week against New Mexico State. "I had a rough week last week. I wanted to make sure I came back."
Byrum did the rest.
"He's got a tremendous leg," Cox said. "I was on the sideline about to throw up. Being a true freshman, after the first time he hit, I was sure he was nervous. To make two of them, that says a lot about him."
The Tigers rushed the field to celebrate and performed the "Gator Chomp" everywhere in front of 90,685 at Ben Hill Griffin Stadium.
The Gators were stunned, much like No. 3 Oklahoma, No. 7 Texas, No. 10 Rutgers and No. 13 Clemson were after being handed their first losses Saturday.
"We couldn't get first downs and we couldn't get the defense off the field," Meyer said. "That's the first time this season we've been put in that position.
"It's very disappointing. We didn't play smart."
Tate finished with 65 yards rushing. Mario Fannin added 62, and Cox was 17-of-26 passing for 227 yards. Smith caught nine passes for 102 yards.
The defense deserves even more credit. The Tigers held Florida to 312 yards, well below its average.
Tebow was 20-of-27 passing for 201 yards with a touchdown and ran 19 times for 75 yards and a score. He got little help, but that was part of the game plan because Meyer was so concerned about blocking the Tigers.
"At no point in that game did I feel comfortable enough to turn around and hand it off," Meyer said.
Florida allowed too many big plays in the first half, the result of too little pressure and too much cushion from cornerbacks.
The offense wasn't much better. The Gators punted on their first two possessions, had a blocked field goal and then fumbled on fourth down just before the half.
They turned it around in the third quarter.
After an Auburn punt, Tebow hooked up with Harvin for 52 yards. They couldn't punch it in from the 3 and settled for a field goal.
Tebow threw his second interception of the season on the next possession, a turnover that helped set up Byrum's 30-yard field goal to take it to 17-3.
Meyer was determined to change the momentum on the ensuing drive and called for a fake punt on fourth-and-1 near midfield. The Gators were flagged for an illegal formation and forced to punt anyway.
Florida got a break, though, when Tate fumbled on the next play. Tebow then took over, eventually connecting with Cornelius Ingram for a 6-yard score that made it 17-10.
After another Auburn punt, Tebow was at it again. He engineered an 89-yard drive, highlighted by a 32-yard pass to Harvin, and tied it with a 2-yard plunge.
Florida had a chance to take the lead, but a shanked punt gave Auburn the ball at the 39-yard line.
Cox, Tate and Byrum took it from there.
"We battled our way back into it, but couldn't get it done," Florida defensive end Derrick Harvey said.