|Northwestern's Pat Fitzgerald celebrates during Saturday's win over Indiana. (US Presswire)|
1. No. 12 Ohio State (5-0): The Buckeyes earned their signature victory of the season thus far when they traveled to East Lansing and won an ugly, defensive battle against the Spartans. It wasn't pretty -- Braxton Miller had three turnovers -- but Ohio State's front seven held Le'Veon Bell to just 45 yards on 17 carries and wide receiver Philly Brown had 12 receptions as Miller's favorite target. Last week's ranking: 1. Next up: vs. Nebraska, Saturday, 8 p.m. ET (ABC).
2. No. 24 Northwestern (5-0): The Wildcats are ranked in both the AP and coaches poll for the first time since 2008 due to their program record 706-yard offensive outburst against Indiana's porous defense on Saturday. Kain Colter, playing wide receiver and running back, accounted for 292 yards and four touchdowns (all rushing). Last week's ranking: 2. Next up: at Penn State, Saturday, 12 noon ET (ESPN).
3. No. 21 Nebraska (4-1): Taylor Martinez led the Huskers' offense to 20 second-half points and tied the second-biggest comeback victory in school history, fighting back from 17 points down against Wisconsin on Saturday. The win sets up next weekend's marquee matchup at Ohio Stadium. Last week's ranking: 4. Next up: at Ohio State, Saturday, 8 p.m. ET (ABC).
4. Purdue (3-1): Caleb TerBush threw for nearly 300 yards and four touchdowns as the Boilermakers defeated Marshall 51-41. Despite giving Notre Dame their best game of the season (20-17 loss), Purdue continues to get no love from the voters and remains unranked heading into the second week of conference play. Purdue gets Michigan at home next weekend and a victory may vault them into the rankings. Last week's ranking: 7. Next up: vs Michigan, Saturday, 4 p.m. ET (Big Ten Network).
5. Michigan (2-2): The Wolverines took a week off of their mediocre play with a bye but get right back to it on Saturday in West Lafayette. Heading into the sixth week of the season, Michigan's best win is still against Air Force. Playing an upstart Purdue team is a tough way to get back on track. Last week's ranking: 6. Next up: at Purdue, Saturday, 4 p.m. ET (Big Ten Network).
6. Michigan State (3-2): After Saturday' 17-16 home loss to Ohio State, it's clear the Spartans never deserved to be included in the national championship picture at the beginning of the season. Evidently installing a first-year quarterback into an offense with few receiving threats is harder than we thought. The Spartans scoring attack ranks 114th in the country with just an average of 20 points per game. Last week's ranking: 3. Next up: at Indiana, Saturday, 12 p.m. ET (Big Ten Network).
7. Minnesota (4-1): The Gophers weak run defense was exposed against Mark Weisman and the Hawkeyes, who ran for 182 total yards and averaged 7.3 yards per carry in the 31-13 win in Iowa City. Minnesota quarterback Max Shortell threw three costly interceptions, including one that was returned 68 yards for a touchdown by Iowa's Christian Kirksey. Last week's ranking: 5. Next up: Idle.
8. Penn State (3-2): The Nittany Lions pounded Illinois this past weekend 35-7 and exacted some revenge for Tim Beckman's dubious recruitment of the Penn State players following the NCAA sanctions. Penn State continues to prove why it's an unbelievably resilient team under the leadership of Bill O'Brien and senior linebacker Michael Mauti, who is playing at an All-American level. Last week's ranking: 9. Next up: vs. Northwestern, Saturday, 12 p.m. ET (ESPN).
9. Wisconsin (3-2): Montee Ball fumbled away a golden opportunity this past weekend at Memorial Stadium to upset Nebraska and prove the Badgers deserve to be a top-tier Big Ten team. Ironically, Wisconsin still has a decent chance to make the Big Ten championship game due to the low standards of the rest of the Leaders Division. Last week's ranking: 8. Next up: vs. Illinois, Saturday, 3:30 p.m. ET (ESPN2).
10. Iowa (3-2): The Hawkeyes are a tricky team to place because they seem to be peaking now that conference play has started. James Vandenberg has finally starting clicking with his receivers and Iowa has a legitimate stud at running back in Mark Heisman, er, Weisman. It will be much easier to place the Hawkeyes following their next game at Michigan State. Last week's ranking: 11. Next up: idle.
11. Indiana (2-2): The Hoosiers deserve credit for hanging tough against Northwestern and giving the Wildcats what they are accustomed to: a second-half scare. Indiana put up 29 second-half points behind its top playmakers in running back Stephen Houston and receiver Kofi Hughes. Last week's ranking: 11. Next up: vs. Michigan State, Saturday, 12 p.m. ET (Big Ten Network).
12. Illinois (2-3): There's not a lot to be optimistic about in Champaign following Saturday's 35-7 blowout against Penn State. It's never a good sign when your running back (Josh Ferguson) throws the team's only touchdown of a game. Last week's ranking: 12. Next up: at Wisconsin, Saturday, 3:30 p.m. ET (ESPN2).
For more Big Ten coverage, follow Mike Singer and Dave Carey @CBSSportsBigTen.