Big Ten power rankings: Week 13

It took a while, but the Big Ten finally has some separation. You've got the top six teams clearly defined. Then you have the next three and finally the three I's -- Indiana, Iowa and Illinois -- at the bottom.

The top three teams remain intact from Week 12, while Penn State and Northwestern move up a spot and Wisconsin moves down despite a good effort against Ohio State. Overall, there's not much movement. Expect a little more shuffling after the final Saturday of the regular season, but at this point, teams have defined themselves as good, average or disappointing.

To the rundown ...

1. Ohio State (11-0, 7-0 Big Ten; last week: 1): Quarterback Braxton Miller and the offense carried Ohio State through the first half of the season. But defense wins championships, and the silver bullets stepped up Saturday at Wisconsin, as linebacker Ryan Shazier and defensive end John Simon triggered an impressive bend-but-don't-break effort. Urban Meyer's team claimed the Leaders Division title and now sits on the doorstep of history, needing a win against archrival Michigan to record the sixth unbeaten, untied season in team history.

2. Nebraska (9-2, 6-1; last week: 2): There was no second-half drama Saturday against Minnesota, as Nebraska surged to 38-0 lead in less than three quarters. Quarterback Taylor Martinez continued his push for Big Ten Offensive Player of the Year honors, becoming Nebraska's career passing leader with 308 yards. Wide receiver Kenny Bell (9 catches, 136 yards, 2 TDs) had another big day, and an improving defense held Minnesota to 11 first downs and 177 yards. Nebraska is one win away from punching its ticket to Indianapolis for the Big Ten title game.

3. Michigan (8-3, 6-1; last week: 3): Devin Gardner, your table is ready. Gardner showed Saturday that Michigan's future on offense is very bright, racking up 314 pass yards on 18 of 23 attempts with six touchdowns (three passing, three rushing) in a rout of Iowa. He is the first Wolverines player to account for six touchdowns since Steve Smith scored three rushing and three passing touchdowns at Minnesota in 1983. Denard Robinson is back in the fold, but Gardner provides the balance Michigan has lacked on offense. Gardner led Michigan to touchdowns on its first six possessions. The Wolverines' chances in The Game against Ohio State look a lot better than they did a few weeks ago.

4. Penn State (7-4, 5-2; last week: 5): It was a bittersweet day for Penn State, which got back on track with a win against Indiana but lost star linebacker Michael Mauti to another apparent knee injury. Senior quarterback Matt McGloin picked apart the Hoosiers for 395 passing yards and four touchdowns, becoming the school's single-season passing leader, while star wideout Allen Robinson had 10 receptions for 197 yards and three touchdowns. Penn State finishes its season this week against Wisconsin at Beaver Stadium.

5. Northwestern (8-3, 4-3; last week: 6): Pat Fitzgerald's crew took another fourth-quarter lead and this time held on, despite losing star running back Venric Mark to injury and going with Trevor Siemian at quarterback instead of Kain Colter. Although Northwestern benefited from four Michigan State turnovers, it took a more aggressive approach in crunch time and recorded a key road win to likely secure a Gator Bowl berth. Siemian, tight end Dan Vitale and others stepped up for the Wildcats, who finish up this week against Illinois in Evanston.

6. Wisconsin (7-4, 4-3; last week: 4): It's a little harsh to drop Wisconsin two spots after an overtime loss to Ohio State, but the move has more to do with both Penn State and Northwestern winning. The Badgers received a terrific defensive performance in regulation and outplayed Ohio State for long stretches, but they couldn't convert yards into points and repeatedly wasted opportunities in Ohio State territory. Montee Ball rushed for 191 yards and a score, and quarterback Curt Phillips made some key throws, but Wisconsin fell short on its home field for the second consecutive game. The Badgers visit Penn State this week before heading to Indy for the title game.

7. Michigan State (5-6, 2-5; last week: 7): Um, yeah, we didn't see this coming, either. Michigan State, picked by both of us and many others to win the Big Ten, needs to beat Minnesota just to get bowl eligible. The Spartans failed to win a Big Ten home game for the first time since 2006 after sweeping their entire home slate in each of the past two seasons. Mistakes once again doomed MSU, which had the edge in total yards, first downs, third-down conversions and many other categories against Northwestern. Andrew Maxwell passed for 297 yards and two scores, but it wasn't enough.

8. Minnesota (6-5, 2-5, last week: 8): Minnesota might be good enough to get to a bowl game, but the Gophers still can't compete with the Big Ten's elite. Jerry Kill's team was overmatched from the onset against Nebraska and never challenged the Huskers in a 38-14 loss. Freshman quarterback Philip Nelson had a rough afternoon, and one of the nation's best pass defenses couldn't stop Martinez, Bell and the Huskers. Minnesota has been a resilient team and must regroup for its finale at home, which would secure a winning season before the bowl game.

9. Purdue (5-6, 2-5; last week: 9): Credit the Boilers for not giving up after an 0-5 start to Big Ten play. Although the season didn't go as expected, Purdue is just one win away from heading to a bowl for the second straight season. The Boilers held off Illinois to record consecutive Big Ten road wins for the first time since 2009. Purdue had a balanced offensive attack triggered by the Akeems (Shavers and Hunt), and unlike last week, it didn't hurt itself with turnovers. Danny Hope's crew now returns home for the Bucket game and can close the season on a three-game win streak.

10. Indiana (4-7, 2-5; last week: 10): Credit the Hoosiers for fighting a lot harder than they did last week against Wisconsin. Cameron Coffman passed for 454 yards and Kevin Wilson got creative with onside kicks. But it's the same story for Indiana's defense, which simply isn't strong enough to stop good Big Ten offenses. McGloin and Penn State had their way with IU, which won't be going bowling and must make significant strides on the defensive side to get to the postseason in 2013.

11. Iowa (4-7, 2-5; last week: 11): Is it over yet? That's all Hawkeyes fans can ask themselves after the team's latest debacle against Michigan at the Big House. Iowa's once-solid defense has completely fallen apart in recent weeks, allowing touchdown drives on Michigan's first six possessions and 513 yards to the Wolverines. The offense continues to stop and start, and Kirk Ferentz's team is assured of its first losing regular season since 2000. Iowa also is mired in its first five-game losing streak since 2000.

12. Illinois (2-9, 0-7; last week: 12): At least the Illini didn't get blown out. Illinois lost a Big Ten game by fewer than two touchdowns for the first time this season, although that's little consolation for a team that has dropped eight straight and five straight on Senior Day. The Illini continued to beat themselves with three fumbles, including two by wide receiver Ryan Lankford. A talented Illinois defense has played better the past two weeks, but Purdue still racked up 207 rush yards. Coach Tim Beckman has emphasized the Northwestern game since his arrival, and an upset of the Wildcats this week in Evanston would be the only bright spot in an otherwise miserable season.