Texas' jump to No. 1 is the largest since Miami went from No. 6 to No. 1 on Aug. 29, 1988, after beating preseason top-ranked Florida State 31-0 to start the season.
Texas received 39 first-place votes and 1,599 points from the media panel. Alabama received the other 36 first-place votes and 1,582 points.
"Being ranked No. 1 shows respect for what we've accomplished through the early part of the season, but nobody really knows who is No. 1 at this point," Texas coach Mack Brown said Sunday.
It certainly has been a fluid situation.
The Longhorns are the fourth No. 1 team this season, following Georgia, Southern California and Oklahoma. So it's just more of the same following an unpredictable 2007 season that had four No. 1 teams and eight different teams ranked second.
For the second time this season, three of the top four teams in the country lost on the same weekend. While the losses by the previously top-ranked Sooners, Missouri and LSU weren't stunning, they did a number on the rankings.
Unbeaten Penn State moved up three spots to No. 3. The Sooners dropped three spots to No. 4 after their first loss. Florida jumped six spots to No. 5 after pounding LSU 51-21 on Saturday night.
No. 6 Southern California is followed by Big 12 rivals Texas Tech and Oklahoma State, which upset Missouri 28-23 and has its highest ranking since November 1985 when the Cowboys were seventh.
No. 9 BYU and Georgia round out the top 10.
Missouri dropped eight spots to No. 11. The Tigers could vault right back up the polls when they play Texas in Austin on Saturday.
"Our team has just played well for six weeks and we know more about where we are today than we did last Sunday, but we have a long way to go and a lot of room to improve," Brown said. "Every week, we're seeing teams learn the hard way that the only poll that matters, or lasts, is the final one. No one remembers who was No. 1 after six weeks last year. If we're No. 1 in late January, it becomes a statement."
Brown and the Longhorns made that kind of statement in 2005. They won the national title after spending the entire regular season ranked No. 2 behind USC, then beating the Trojans 41-38 in the Rose Bowl.
Ohio State is 12th and LSU is 13th, a nine spot drop after getting drubbed in the Swamp.
No. 14 Utah, No. 15 Boise State and No. 16 Kansas all held their spots. No. 17 Virginia Tech was followed by North Carolina, which jumped four spots after beating Notre Dame 29-24.