The top-rated defense in college basketball did not play like it last night. Fortunately for Ohio State, William Buford finally played like his old self again.

Seven straight points by the Buckeyes’ slump-ridden senior broke open a tie game in the last five minutes and third-ranked Ohio State held on in its closest home game of the season to turn back Purdue 87-84 in Value City Arena.

Buford scored 21 points in the second half and finished with a career-high 29 for the Buckeyes (21-3, 9-2 Big Ten), who maintained sole possession of first place in the Big Ten.

“Offensively, I knew I had to pick it up,” said Buford, whose run came with Jared Sullinger and Aaron Craft on the bench with four fouls apiece.

Sullinger scored 18 points but, after returning to the floor with 1:25 remaining, limped off 18 seconds later after appearing to fall on his left side after trying to rebound a missed Purdue shot. He did not return.

“It felt a little funny. I didn’t want to risk injuring myself worse,” Sullinger said.

There was no immediate word from Ohio State on the nature of the injury.

“We’ll find out,” Sullinger said when asked if it was serious.

The win was Ohio State’s 39th in a row at home since a 60-57 loss to Purdue on Feb. 17, 2010.

D.J. Byrd led Purdue (15-9, 5-6) with a career-high 24 points, including seven three-pointers. He had 17 points in the first half before guards Kelsey Barlow and Lewis Jackson took advantage of the Buckeyes’ loose defense inside in the second by driving for baskets. Barlow and Jackson finished with 14 points apiece.

Both teams shot better than 50 percent from the field.

The score was tied at 73 with under five minutes remaining before Buford made three straight perimeter jumpers in a 96-second span. The last, a three-pointer from the top of the key, gave the Buckeyes an 80-73 lead with 2:54 remaining.

“I haven’t been worried about Will,” Ohio State coach Thad Matta said. “He hasn’t been making shots, but nobody makes them all.

“When you look at everything he’s been a part of here, I’ve got great confidence in him, and I’ll never lose it.”

After Buford’s barrage, Purdue got back within four points twice in the final 67 seconds but never had a chance to tie or take the lead again.

Robbie Hummel’s three-pointer in the closing seconds cut the final margin to three.

“I thought we played well enough to win. We just didn’t get the breaks at the end,” said Purdue coach Matt Painter, who said he shook up his starting lineup for the game looking for “a response,” and got it.

After playing the Buckeyes to a first-half tie, Purdue started the second half with a three-point play by Barlow. It marked the first time in 21 home games the Buckeyes had trailed in the second half. They had trailed only twice in the second half during the 38-game home win streak they took into the game.

Barlow continued to take advantage of his matchups with repeated drives to the hoop in the next 12 minutes, especially against Craft, who went to the bench with his third and then fourth fouls as the lead went back and forth between the teams.

But the Boilermakers could not shake Ohio State, which did not fall more than three points behind at any point and finally was able to forge an 80-73 lead with 2:54 left on Buford’s seven-point spree.

The Buckeyes held the lead with bench players Evan Ravenel, Shannon Scott and Sam Thompson on the floor.

“Every game in the Big Ten is a dogfight,” Craft said. “I think guys are starting to understand every game is going to be a tough one. We have to find a way to win, and we did that tonight.”

bbaptist@dispatch.com