Ohio State still sits atop the Power Rankings, but there has been a significant shake-up after the Buckeyes.

Wisconsin's impressive victory against lifeless Northwestern vaults the Badgers to No. 2, as we consider Gary Andersen's team the closest to Ohio State at this point in the season. Northwestern takes a significant tumble, and Michigan also falls after failing to pull off another escape against Penn State. Nebraska and Michigan State are taking care of business against weak competition, which helps both teams now but won't mean much when the schedule gets tougher in November.

Penn State makes a move in a positive direction following its dramatic win against Michigan in four overtimes. The bottom of the rankings holds steady as most teams were off.

Here's one last look at the Week 6 rankings.

Week 7 rankings in three, two, one …

1. Ohio State (6-0, 2-0 Big Ten; last week: 1): After two hard-fought victories to open Big Ten play, the unbeaten Buckeyes had a well-deserved week off. Their young defensive front seven is starting to blossom, which should help against Iowa's power run game on Saturday at The Shoe. Running back Carlos Hyde takes aim at an Iowa defense that has yet to allow a rushing touchdown. Ohio State is halfway to another perfect regular season.

2. Wisconsin (4-2, 2-1; last week: 3): The Badgers looked refreshed, recharged and exceptionally prepared for Northwestern following their open week. Wisconsin's defense completely flustered Northwestern, particularly on third down, where the Wildcats typically excel. Melvin Gordon did his thing and Wisconsin moved the ball despite playing without top receiver Jared Abbrederis for most of the game. The schedule is favorable the rest of the way and a 10-2 mark is hardly out of the question. Wisconsin visits Illinois this week.

3. Nebraska (5-1, 2-0; last week: 5): Credit Nebraska for handling its business against inferior competition and not even flirting with a loss for the second consecutive Big Ten game. The defense once again took a step forward as one-time Purdue recruit Randy Gregory had two tackles for loss and a fumble recovery. Backup quarterback Tommy Armstrong Jr. struggled, but he had plenty of help from the run game, led by Ameer Abdullah (126 rush yards, 1 TD). The Huskers once again are off this week, which should allow top signal-caller Taylor Martinez to heal from his toe injury.

4. Michigan State (5-1, 2-0; last week: 6): Defense always will be the Spartans' bread and butter, but Michigan State is capable of winning games with its offense. Sure, Indiana's defense isn't a great barometer, but Spartans fans have to be encouraged by quarterback Connor Cook, running back Jeremy Langford and a unit that seems to be gaining more confidence by the week. Like Nebraska, Michigan State is handling its business during a favorable stretch of the schedule, which continues this week against flailing Purdue.

5. Michigan (5-1, 1-1; last week: 2): The Wolverines twice had flirted with losing in their first five games, only to find a way to pull through. They nearly pulled off another escape at Penn State after a strong second half, but breakdowns in all three phases led to a crushing loss in four overtimes. The defense broke down at the end of regulation, the offense couldn't find the end zone in overtime and the normally reliable Brendan Gibbons missed three attempts (one was blocked). Michigan will need to grow up in a hurry to challenge for the Legends Division title.

6. Northwestern (4-2, 0-2; last week: 2): It's a four-spot drop for the Wildcats, and that might be kind after the egg they laid Saturday in Madison. Northwestern clearly had a hangover from the Ohio State game, although there are some troubling trends on offense, namely the inability to covert manageable third downs, which has been a hallmark of past Wildcats teams. The injuries are piling up for Pat Fitzgerald's crew, as Venric Mark (ankle) barely played and Kain Colter (ankle) didn't do much at quarterback. Northwestern really needs to get well this week against Minnesota.

7. Penn State (4-2, 1-1; last week: 9): What do we make of Bill O'Brien's Lions? A week after Penn State's first loss to Indiana -- by 20 points, no less -- the Lions rebounded to outlast Michigan 43-40 in a four-overtime thriller. O'Brien played to win while Michigan's coaches went conservative, and freshman quarterback Christian Hackenberg rebounded from some mistakes to lead the game-tying touchdown drive at the end of regulation. This Penn State team isn't as good as its predecessor, but it exhibits the same type of resilience and toughness. Penn State gets a well-deserved week off before heading to Ohio State.

8. Iowa (4-2, 1-1; last week: 7): The open week arrived at a good time for Iowa, which came out of the Michigan State loss with several injuries, although none of the long-term variety. The Hawkeyes need to reboot Mark Weisman and the run game after being shut down by the Spartans. Iowa's defense faces its first major test of the season in Ohio State, which will try to stretch the field. The Hawkeyes last won in Columbus in 1991.

9. Indiana (3-3, 1-1; last week: 8): The inconsistency that has plagued Indiana through the first half of the season showed up Saturday against Michigan State. The offense had more success against Michigan State's venerated defense than most opponents but still left points on the field. Indiana's defense, meanwhile, took a step back as the Spartans had success both on the ground and through the air. The Hoosiers' quarterback situation took another turn as Tre Roberson outperformed Nate Sudfeld. IU heads back to the Mitten State this week to face Michigan.

10. Illinois (3-2, 0-1; last week: 10): The Illini didn't play for the second time in four weeks after struggling on both sides of the ball at Nebraska. If Tim Beckman's squad intends to go bowling, it might need a home upset victory in the next two weeks as it hosts Wisconsin and then Michigan State. Illinois hopes to get defensive lineman Teko Powell back from injury before facing the dominant Wisconsin rush attack. Quarterback Nathan Scheelhaase must rebound after completing only 50 percent of his passes against Nebraska.

11. Minnesota (4-2, 0-2; last week: 11): Adversity continues for the Gophers as head coach Jerry Kill has taken a leave of absence as he tries to get his epilepsy under control. Although Minnesota assistants and players know how to adjust without Kill, it doesn't make the situation much easier. The big on-field concern for the Gophers is the schedule, which doesn't get any easier this week against Northwestern. The Gophers are still looking for more explosiveness on offense.

12. Purdue (1-5, 0-2; last week: 12): There will be better days ahead for Danny Etling and the Boilers, but it's very ugly right now. Purdue never challenged Nebraska at Ross-Ade Stadium, and the Boilers' problems on offense clearly go beyond the quarterback position as Etling couldn't get much going. Purdue didn't cross midfield until the fourth quarter. The defense had no answers for Nebraska, which piled up 435 yards. This is a really bad football team, folks, and things don't get easier with Michigan State and Ohio State to follow.