For the first time this season, Illinois has to bounce back from a loss.

Ohio State reserve forward Matt Sylvester hit a 3-pointer with 5.1 seconds left yesterday to hand the top ranked Illini their first defeat, 65-64.

Ohio State’s victory was the biggest of several upsets on the final day of action before the major conferences begin their tournaments. Four of the top seven ranked teams in the country were beaten, including no. 3 Kentucky, which lost to Florida,53-52; no.7 Kansas, which fell to Missouri, 72-68; and no. 6 Duke, which narrowly missed a chance to beat no. 3 North Carolina, falling 75-73.

The Illini (29-1, 15-1) were trying to cap the Big Ten’s first unbeaten season in 29 years. Instead, they frittered away a 12-point lead in the second half and didn’t score over the final 3 minutes.

“Everyone says a loss will help. We’ll find out,” coach Bruce Weber said. “We’ll learn from it and move on. This next stretch is the most important of the year and that’s what people are going to remember.”

Sylvester scored a career-high 25 points – eight more than his previous best – for a team that was banned by its own administrators from the postseason two months ago to mitigate possible NCAA violations committed under former coach Jim O’Brien.

First-year coach Thad Matta drew up a play in which center Terence Dials set a pick and rolled to the basket and guard Tony Stockman was used as a decoy. The Illini bit on the deception.

After a timeout, a pass was tipped out of bounds in front of the Illinois bench. The Illini had one last chance with 2.2 seconds left. Junior Deron Williams passed to senior forward Roger Powell, but his hurried 3-pointer from the top of the circle was well short and off the mark.

Ohio State (19-12, 8-8), a team with problems all year hanging onto the ball, didn’t have a turnover in the second half. The Illini, who had hurdled tough games in loud environments all season, had seven turnovers after halftime.

It was the second straight season a team coached by Matta ended a run at perfection. Matta’s Xavier team handed Saint Joseph’s its first loss last season in the Atlantic 10 tournament.

“I’d like to be the other team just one time,” Matta said with a laugh. “I’m living for the day I’m the no. 1 team and someone else is trying to do it to us.”

The last team to reach the NCAA tournament without a loss was UNLV in 1991. On Saturday, Matta had shown his players film clips of several huge upsets and the Rebels’ loss to Duke in the national championship game that year was one of them.

The Illini led 64-58 after James Augustine’s layup with 3:23 left – but didn’t score again.

Dee Brown led the Illini with 13 points, although he was rattled all day by chants of “air ball” after several errant second-half shots. He was 3-of-11 from the field and had only five points over the final 34 minutes. Powell and Luther Head each added 12 points.

Foster added 10 points for Ohio State, which enters this week’s Big Ten tournament as the no. 6 seed. After that, the Buckeyes will head home.

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NO. 3 UNC 75, NO. 6 DUKE 73

Freshman Marvin Williams had it all in his hands – the game, the outright Atlantic Coast Conference title, and a probable no. 1 seed in the NCAA tournament. He handled the pressure like a veteran.

The dynamic forward converted a three-point play with 0:17 left to cap North Carolina’s game-closing 11-0 run and give the second-ranked Tar Heels a 75-73 win over no. 6 Duke yesterday.

North Carolina’s Sean May had 26 points and 24 rebounds to record his eighth straight double-double, and his final rebound was the most important. After J.J. Redick missed a long 3-pointer that would have won it for the Blue Devils, teammate Daniel Ewing had a final chance from just inside the arc.

But his shot was short, and May leaped high for the carom. He cradled the ball in his hand while the clock ran out, then hurled it into the stands. Hundreds of fans rushed the court to celebrate the Tar Heels’ third victory over their Tobacco Road rivals in the past 16 meetings.

North Carolina (26-3, 14-2) won its first ACC regular-season championship since 1993, the same year of its most recent national title.

Shelden Williams had 25 points and six blocks for Duke (22-5, 11-5), which played without guard Sean Dockery for the third straight game. Redick scored all 17 of his points in the first half.

Even without Redick scoring at his usual pace, the Blue Devils seemingly had control late in the second half. They broke from a tie at 64 with a 9-0 run, capped by a 3-pointer by Lee Melchionni with 3:07 left. That was his fifth 3 of the second half and it gave Duke a 73-64 lead. The Blue Devils didn’t score again.

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FLORIDA 53, NO. 3 KENTUCKY 52

Anthony Roberson scored 21 points, including two free throws with 15 seconds remaining, and Florida upset no. 3 Kentucky 53-52 yesterday.

The Gators ended an eight-game losing streak to Kentucky and probably ended the Wildcats’ hopes of getting a top seed in the NCAA tournament.

Roberson, the Southeastern Conference’s leading scorer, stripped the ball from Patrick Sparks with about 12 seconds to play, trailing 52-51. Sparks fouled Roberson as he headed the other way. Roberson stepped to the line and calmly made both ends of the 1-and-1.

The outcome didn’t change either team’s seeding for next week’s SEC tournament, but it could drastically alter their seeding in the NCAA tournament. Kentucky (23-4, 14-2) should fall in the polls, and even if the Wildcats win a third straight SEC tournament, it might not be enough to claim one of the top four seeds.

Florida (20-7, 12-4) could return to the Associated Press’s Top 25 for the first time since late November and will likely improve their NCAA seeding.