They got the Hawkeyes back in Iowa City behind a signature performance from senior Aaron Craft.
Craft had 17 points with six assists and six steals to help Ohio State upset 17th-ranked Iowa on Tuesday night 76-69 for its third win in four games.
LaQuinton Ross added 13 points for the Buckeyes (18-5, 5-5 Big Ten), who moved back to .500 in the league after starting a surprising 2-4.
Craft had 14 of his points in the first half, and his three-point play put Ohio State ahead 66-59 with 1:17 left.
That sealed back-to-back road wins for the surging Buckeyes, who answered a loss to Penn State by beating Wisconsin 59-58 on Saturday.
''It's huge, and it's not big because people were doubting us or people aren't behind us anymore. This is just big for us,'' said Craft, whose defense also helped limit Iowa star Devyn Marble to 4 of 11 shooting. ''If there's anything that we've learned from this year is that it doesn't matter about anything that is said outside of our locker room.''
For Iowa, this might have been the low point it had avoided to this point.
Mike Gesell had a season-high 16 points to lead the Hawkeyes (17-6, 6-4), who shot just 3 of 20 from 3-point range. They lost their second straight at home and their first to an unranked opponent - and Marble and Aaron White combined for just 18 points.
''We played hard. We didn't play well. We never really got in sync,'' Iowa coach Fran McCaffery said.
The Hawkeyes clearly wanted to attack Ohio State from the perimeter. But they missed all but one of their first 14 3s, and the Buckeyes were able to manage a slim lead for most of the second half.
Iowa rallied to within 58-54 before Williams threw down a dunk off an inbounds pass with just two seconds left on the shot clock. Sam Thompson then buried a 3 for a 63-54 lead with 3:56 to go.
''I think we've finally found our groove,'' Williams said. ''We're playing together, and I think once we continue to play together as a team we're one of the best teams in the Big Ten.''
Williams and Lenzelle Smith Jr. each had 12 points for Ohio State, which won despite a 38-25 deficit on the boards. It certainly helped that Iowa was just 12 of 19 from the free throw line.
Olaseni had 14 points, six rebounds and a pair of blocks off the bench.
Iowa fell 2½ games behind idle Michigan and Michigan State in the league standings with eight to play. Iowa hosts the Wolverines at home on Saturday.
''We lost the game with defense in the second half,'' McCaffery said.
Iowa soundly defeated Ohio State in their first meeting, rallying from nine down to win 84-74. At the time it seemed like a breakthrough road win for the Hawkeyes -- a sign the program had truly arrived under McCaffery.
But the Buckeyes unexpectedly kept losing and fell out of this week's Top 25 poll.
It was Iowa that looked like the unranked early though. The Hawkeyes fell behind by as much as 26-17 until a play more suited for the football field gave them the lead at halftime.
Marble and Gesell trapped Craft near half court. Marble stripped the ball and hiked it under his legs to Gesell, who then chucked the ball like a post pattern to a waiting Aaron White for a slam dunk.
That would prove to be a rare miscue from Craft -- and plays like that were few and far between for the Hawkeyes.
''I thought our halfcourt defense was as good as it can be,'' Ohio State coach Thad Matta said.
Like he has so often during his brilliant career, Craft was the focus of an Iowa crowd that heckled him at every turn. But he and the Buckeyes had the final say.
''It was intense. They got after it a little bit. But you just try to do your best to knock it all out. And the best way to get back at them is to make them go home quiet like they did [Tuesday] night,'' Craft said.