By Chris Emma-

(CBS) If one game could best define this Big Ten season, it’s Nebraska’s 60-51 road upset of ninth-ranked Michigan State.

The unpredictable Big Ten revealed a new wrinkle on Sunday when the Cornhuskers — picked last in preseason polls — took down the conference’s top team, doing so in the hostile Breslin Center. It took 23 points from Terran Petteway and a stellar defensive effort to shut down the Spartans on their home court. Now, the Big Ten is in total limbo.

With the Spartans’ loss and Michigan falling to the Badgers, Iowa and Wisconsin are a legitimate threat in the regular-season race. Meanwhile, Nebraska and Minnesota have real NCAA Tournament hopes.

Among the few certainties in this league are Iowa’s offense, Ohio State’s defense and Tim Miles’s Coach of the Year chances. Aside from that, it’s hard to predict anything on any given night. That’s just how the Big Ten is this year.

Power Rankings

1. Michigan State (21-5, 10-3) – There’s no denying that Michigan State’s 21-5 record is impressive, but it doesn’t reflect the Spartans’ recent play. An injury-riddled team has been wildly inconsistent. MSU could easily be a Final Four team, but an early exit in the tournament is just as possible.

2. Wisconsin (21-5, 8-5) – The Badgers appear to have regained composure after a mid-season slip. Wisconsin is climbing up the Big Ten standings with four wins in a row, and proving it’s a threat for a deep run in March.

3. Michigan (18-7, 10-3) – The joys from a road victory against rival Ohio State were quickly washed away after Michigan was thumped by Wisconsin on its home court. The Big Ten’s co-leaders have a week to prepare for their battle with Michigan State on Sunday.

4. Iowa (19-6, 8-4) – Perhaps the only Big Ten team showing signs of consistency, the Hawkeyes are still right in the hunt for the conference’s regular-season crown.

5. Nebraska (14-10, 6-6) – Remember when Nebraska was picked last in the Big Ten’s preseason polls? That seems like a long time ago for a Cornhusker team that’s reeled off three straight wins, including the upset in East Lansing.

6. Ohio State (20-6, 7-6) – An ugly win is better than a pretty loss. For Ohio State, a lackluster win over Illinois was much needed to get back on track.

7. Minnesota (17-9, 6-7) – Don’t sleep on Richard Pitino’s team. The Golden Gophers got back at Northwestern with an important road win. Now, Minnesota’s schedule sets up for a potential strong finish and tournament berth.

8. Northwestern (12-14, 6-7) – The Wildcats were rolling until their first full week off, which oddly has led to a three-game skid. Star guard Drew Crawford went 1-for-15 in NU’s loss to Minnesota. Suddenly, postseason hopes are fading in Evanston.

9. Purdue (15-10, 5-7) – Maybe a win over rival Indiana will boost the Boilermakers to a strong finish. But it’s hard to count on anything for an inconsistent team.

10. Penn State (13-13, 4-9) – The least-lethargic of the Big Ten’s three bottom-dwellers, Penn State saw a split with a comeback win at Indiana then a slipup against Iowa.

11. Indiana (14-11, 4-8) – It was the worst week in Bloomington since the dark days of Tom Crean’s first seasons. First, the Hoosiers saw their 12-point lead vanish in the final minute of a home loss to Penn State, then were blown out by the rival Boilermakers. All hope is lost for a once-promising season.

12. Illinois (14-12, 3-10) – OK, maybe there is something certain in the Big Ten. The Fighting Illini remain an absolute wreck, having dropped 10 of their last 11 games.

Three-Point Play

1. Petteway leading the Huskers

Look atop the list of the Big Ten’s scoring leaders and an unfamiliar name is right behind the leader. Nebraska’s Terran Petteway has put together a stellar season, averaging 17.7 points per game and leading the upstart Cornhuskers.

Nebraska saw its share of offensive struggles in the first season of Tim Miles. Now, Petteway has shown he can lead the charge on offense. The Huskers have hope for a tournament berth and they have Petteway to thank.

2. Indiana trending the wrong way

It seemed like Tom Crean had the Hoosiers back on track before this season. But suddenly, Indiana has taken a dip toward the bottom of the Big Ten. Youth isn’t an excuse anymore for Indiana, not with the season coming to a close. It’s just a sloppy team, and much of that blame falls on the coach.

3. A check on Maryland and Rutgers

In a little over a year from now, the Big Ten will be readying for a 14-team conference tournament as Maryland and Rutgers will be part of the mix. The two newcomers have seen struggles in their final year before joining the conference.

Maryland’s record sits at 14-12 overall and 6-7 in the loaded ACC, but the conference mark won’t matter as much amid a rough season. It will take a late run for the Terps to make the tournament. As for Rutgers, a 10-16 mark speaks for itself. There hasn’t been much going right for new coach Eddie Jordan and the Scarlet Knights.

Player of the week: Terran Petteway, Nebraska guard – Simply a no-brainer for this honor, Petteway posted 16 points in a win over Illinois, then followed it on Sunday with 23 in the upset of Michigan State.

Team of the week: Nebraska – Another easy pick. Any team that wins in East Lansing deserves a tip of the hat, but the Cornhuskers proved they’re for real with their impressive victory.

Chris Emma covers the college sports scene for CBSChicago. Follow him on Twitter @CEmmaScout.

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