With the 'Zags taking over #1, Indiana fell to 2nd.
Ohio State used a pair of wins to move up to 14th and three B1G teams are still in the top 10.
Gonzaga becomes the 5th team to be ranked #1 through Week 18. Not since 2003-04 has more than five teams held the top spot to this point in the season.
The 'Zags are also just the third non-BCS team in the history of the AP Poll to be ranked #1 joining Memphis (2007-08) and St. Joseph's (2003-04).