ESPN College Football

The ides of the 2005 college football season are upon us, and much has changed since kicking things off six weeks ago. Michigan opened the season as the No. 4 team in the country, but three losses in six tries have resulted in its top 25 exodus. Oklahoma, Iowa and Purdue are three other preseason top 15 teams that followed the Wolverines' lead. But one program's disappointment typically signals an opening for another. Traditional powerhouse programs such as Alabama, Notre Dame and Penn State seized the opportunity and have re-emerged among college football's elite.

As a result of all that fluctuation at the top of the polls, some matchups that looked unappetizing in the preseason have suddenly taken on new meaning. Some games are meaningful regardless of records -- just ask fans of Ohio State and Michigan, Auburn and Alabama, Florida and Georgia, UCLA and USC, and so on. Fortunately, it just so happens that most of college football's great rivalries also project to have a major impact on the college football landscape by season's end.

With nine undefeated teams and every major conference title still up for grabs, marquee matchups are easy to find. As we look forward to the second half of the 2005 season, here are the games that promise to be most meaningful:

To continue reading this article you must be an Insider