The Crimson Tide swayed more than enough voters in both polls with a 41-14 win Saturday night at Cowboys Stadium to overtake the preseason No. 1 Trojans, who beat Hawaii 49-10. USC entered that game a 40-point favorite at home.
Alabama received 45 first-place votes in the AP poll, up 28 from last week, and 37 first-place votes in the USA Today coaches' poll.
It marks the 47th time that Alabama has been No. 1 in the AP poll, the 16th under coach Nick Saban.
"I would agree with (voters)," USC coach Lane Kiffin said Tuesday. "I didn't watch any of the game because we can't, but from what I heard, they played a really good Michigan team in a big matchup and played really well."
This is the 86th time in the 76-year history of the AP poll that the top-ranked team won and dropped in the rankings. It's happened at least once every year since 2007.
Despite their season-opening blowout, the Trojans received 11 first-place votes in the AP poll and 14 in the USA Today poll.
Asked if losing the No. 1 ranking motivated him, USC quarterback Matt Barkley said, "I don't care about it. It doesn't motivate me. A ranking doesn't motivate me. I think being perfect is what motivates us."
Both polls have the same top seven, with LSU at No. 3. Oregon and Oklahoma round out the top five in both polls, followed by Florida State and Georgia. Michigan fell the same number of spots in both polls, dropping 11 places to No. 19.
Notre Dame coach Brian Kelly downplayed his team's rise in the poll Tuesday, called the ranking "white noise."
Boise State fell out of the Top 25 thanks to Friday's loss at Michigan State, marking the first time in 62 weeks that the Broncos are unranked in the AP poll. That was the second-longest active streak, behind Alabama (now at 67).
The Mountaineers climbed three spots to No. 8 in the USA Today poll, and the Gamecocks and Razorbacks rounded out the top 10. Louisville joined the USA Today poll at No. 24.
Information from ESPNLosAngeles.com's Pedro Moura and The Associated Press was used in this report.