CHAMPAIGN, Ill. — Less than two weeks ago, Michigan State had its hands firmly locked on the Big Ten lead. The Spartans had a two-game edge on their closest challengers — unranked and unimpressive Illinois and an Ohio State team with some early conference losses.

That all seems so long ago.

The 10th-ranked Spartans have dropped three straight while the still-unranked Illini and No. 13 Buckeyes have each won five in a row, creating a three-team jam at the top of the conference. After some early Big Ten losses, No. 6 Purdue is just a half-game back with No. 11 Wisconsin in third place one game behind the leaders.

“You can’t ever feel good in college sports,” Ohio State coach Thad Matta said. “That’s one of the beauties of playing in the Big Ten — if you don’t come ready, you’ll get embarrassed.”

The Spartans won their first nine conference games, but this week felt the sting of what Matta was talking about.

“We’re going through a little lull like Purdue went through and Ohio State went through,” coach Tom Izzo said, adding that his team sometimes lacks a sense of urgency. “I tried to say it for a month when we were winning, and I say it now that we’ve (lost a few).”

Injuries have had a hand in the Big Ten upheaval. Michigan State guard Kalin Lucas, the team’s leading scorer, is hobbled by an ankle injury that forced him to miss one game and Ohio State’s Evan Turner had a serious back injury.

But ask the Big Ten coaches to explain what’s happened the past couple of weeks and they point to their opponents and how their teams have played on the road. Michigan State (19-6, 9-3 Big Ten) dropped games at Wisconsin and Illinois before losing at home to Purdue.

“I think it’s more because who we’re playing and where we’re playing them,” Izzo said. “I was pleased with everything we did in the Illinois game except turn the ball over.”

The Illini are one of the more intriguing teams in the league, dropping three in a row last month but winning games they had to win (Penn State, Iowa and Indiana) to stay alive in the Big Ten race.

“That’s one thing about this team: We don’t get down on ourselves,” Illinois guard Demetri McCamey said Tuesday night after the team handed Wisconsin a rare home loss. “We’re always picking up a teammate.”

And if you’re going to blame Illinois (17-8, 9-3) for the jumbled state of the Big Ten, single out McCamey. He was benched for two games in January but has since averaged 18.8 points and 7.2 assists a game and is becoming the leader coach Bruce Weber had hoped for.

“We’ve got ourselves where we’re a little bit of a contender, but we have a long way to go and a very tough schedule ahead of us,” Weber said.

That starts Sunday with a visit by Ohio State (19-6, 9-3).

Matta’s Buckeyes have been the other Big Ten spoiler, bouncing back from a 1-3 conference start that included losses to Michigan and Minnesota. Turner’s return to the lineup after a month off with two broken bones in his back has been the key.

Turner is the leading scorer (19.2 ppg) and rebounder (9.3 rpg) in the Big Ten. He’s also the Buckeyes’ undisputed leader, and the catalyst for whatever they accomplish this season.

“Like Evan preached before the season started, we don’t want to come to Ohio State and leave without leaving our mark, with anyone just saying ’They were a pretty good team but, really, what did they do?”’ Buckeye junior David Lighty said. “Pretty much, a Big Ten championship is the start and then whatever happens after that, falls in line. Hopefully, a NCAA Final Four run.”

The Illini have probably the toughest remaining schedule of the Big Ten contenders, with games against Purdue (20-3, 8-3), Wisconsin (18-6, 8-4) and two meetings with Ohio State. On paper, Wisconsin has the easiest schedule: six games and only one — at Illinois — against a team with a winning Big Ten record.

None of the conference’s top teams has any reason to think they’re out of the race, Wisconsin center Keaton Nankivil said.

“As much of a cluster the Big Ten is, there is no reason to dwell on one loss,” he said. “We just have to go out and play and do everything we can to get back in a good position.”