Associated Press

The upset bug came back with a vengeance in Week 5 of the college football season.

Four Top 10 teams lost to lower-ranked opponents, including a pair of SEC powers that lost big cross-divisional games by the exact same scoreline. The early favorite in the Pac-12 was stunned at home by a two-loss team, and the weekend's biggest game ended in heartbreak for the comeback-minded visitors.

Elsewhere, the nation's top two teams looked less than impressive in Big Ten play, while two Big 12 leaders lit up the scoreboards on Saturday.

The combination of all these results should make for some interesting ballots in the Week 6 Associated Press poll, which makes this week's task of projecting the Top 25 the toughest challenge of the young season.

As always, here's this week's prediction for the upcoming AP poll and some special spotlights on the biggest rises and falls in the Top 25.

Predicted Week 6 Associated Press Poll Team Previous Record Week 5 Result 1. Ohio State 1 5-0 Won 34-27 at Indiana 2. TCU 4 5-0 Won 50-7 vs. Texas 3. Michigan State 2 5-0 Won 24-21 vs. Purdue 4. Baylor 5 4-0 Won 63-35 vs. Texas Tech 5. LSU 9 4-0 Won 44-22 vs. Eastern Michigan 6. Utah 10 4-0 BYE WEEK 7. Clemson 12 4-0 Won 24-22 vs. No. 6 Notre Dame 8. Alabama 13 4-1 Won 38-10 at No. 8 Georgia 9. Florida State 11 4-0 Won 24-16 at Wake Forest 10. Texas A&M 14 5-0 Won 30-17 vs. No. 21 Mississippi State 11. Oklahoma 15 4-0 Won 44-24 vs. No. 23 West Virginia 12. Florida 25 5-0 Won 38-10 vs. No. 3 Ole Miss 13. Northwestern 16 5-0 Won 27-0 vs. Minnesota 14. Stanford 18 4-1 Won 55-17 vs. Arizona 15. Notre Dame 6 4-1 Lost 24-22 at No. 12 Clemson 16. Ole Miss 3 4-1 Lost 38-10 at No. 25 Florida 17. USC 17 3-1 BYE WEEK 18. UCLA 7 4-1 Lost 38-23 vs. Arizona State 19. Georgia 8 4-1 Lost 38-10 vs. No. 13 Alabama 20. Oklahoma State 20 5-0 Won 36-34 vs. Kansas State 21. Michigan 22 4-1 Won 28-0 at Maryland 22. Iowa NR 5-0 Won 10-6 at No. 19 Wisconsin 23. California 24 5-0 Won 34-28 vs. Washington State 24. Toledo NR 4-0 Won 24-10 vs. Ball State 25. Boise State NR 4-1 Won 55-0 vs. Hawaii Justin Ferguson

Who's No. 1?

Ohio State's narrow win at Indiana on Saturday should've swung the door open for a new team to vault into the No. 1 spot in the AP poll. With Michigan State having to hold onto a tight home win against Purdue, it seemed to be Ole Miss' chance to make the big jump.

But the Rebels—more on them later—fell flat on their faces against Florida in the Swamp.

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With No. 2 failing to impress and No. 3 losing on the road, Ohio State will most likely hold onto No. 1 in the AP poll. While TCU and Baylor can make their own strong claims to the top spot, I'm siding with the opinion of the AP's own Ralph D. Russo.

"Winning ugly was fine for Florida State last year because the Seminoles won them all until the semifinals," Russo wrote. "Ohio State will likely be afforded the same courtesy. As would pretty much any team from a Power Five conference."

Last year's Florida State team, one that is looking eerily like this year's Ohio State squad, didn't lose its No. 1 spot in the poll until Mississippi State recorded a huge win over then-No. 2 Auburn. Since no other Top Five team has pulled off a win of that magnitude yet, the Buckeyes should survive at No. 1 for another week.

Moving up

Florida

After breaking into the Top 25 last weekend following a comeback win over a falling-apart Tennessee team, Florida proved it was for real Saturday night by hammering No. 3 Ole Miss at home.

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Behind an outstanding performance from quarterback Will Grier, the Gators opened up a 25-0 halftime lead, and the defense didn't allow a touchdown to Ole Miss' normally potent offense until the 4:04 mark of the fourth quarter. Let's be clear—Florida owned this matchup from the start.

Florida now has the most impressive win of the season after smashing a team that entered the weekend with the second-most No. 1 votes in the AP poll.

That huge victory should be enough for the Gators to leap over a logjam of one-loss teams and also undefeated Northwestern, which doesn't have as shiny of a resume as Florida.

TCU

While TCU might not have enough firepower to jump all the way to No. 1 in the country—the Horned Frogs slipped from a tie at No. 3 to No. 4 last weekend after a narrow win at Texas Tech—it should get a boost this weekend in the polls.

Ron Jenkins/Associated Press

TCU destroyed one-win Texas by a score of 50-7 at home Saturday. Trevone Boykin was excellent again, but the real impressive story was a banged-up TCU defense shutting down a Texas offense that had somewhat started to turn a corner.

"It built a lot of confidence for our defense," TCU cornerback Nick Orr said, per Chuck Carlton of the Dallas Morning News. "We knew we gave up 52 points last week, but [we] came out this week locked and focused, which made up for it."

With Michigan State losing momentum with another closer-than-expected home win, don't be surprised if TCU takes full advantage with a move into No. 2—that is, if lower-ranked Baylor doesn't surprisingly jump both programs.

Clemson and Alabama

Clemson almost blew an 18-point second-half lead Saturday night against Notre Dame, but the Tigers held on to record a huge home win over the higher-ranked Fighting Irish. While its offense was held to fewer than 300 yards, Clemson's defense forced four turnovers and made a huge stop to deny what would've been a game-tying two-point conversion.

Joshua S. Kelly-USA TODAY Sports

With Florida State failing to impress away from home in ACC play against Wake Forest, I have the Tigers jumping the Seminoles and sliding right behind idle Utah in this week's poll.

Meanwhile, Alabama reignited its playoff push with a massive road blowout victory over previously undefeated Georgia. Outside of a pair of fumbles and a long touchdown run by Georgia superstar Nick Chubb, Alabama played a completely dominant game of football between the hedges.

Even with its one loss to Ole Miss, Alabama should have enough momentum to also vault over Florida State, which started the weekend two spots ahead. The Tide looked like a total contender again in Athens.

Moving down

Ole Miss

The talk surrounding Ole Miss turned on a dime this weekend after its ill-fated trip to the Swamp. The Rebels seemed to be knocking on Ohio State's door with a favorable-looking schedule in the early part of October.

Phelan M. Ebenhack/Associated Press

But Ole Miss looked nothing like a championship contender against Florida, turning the ball over four times and not putting points on the scoreboard until the second half. This, of course, is the same Ole Miss team that scored 76, 73 and 43 points in its first three games of the season.

"We really needed the game early on to go back-and-forth a little bit and stay close and let us figure a few things out," Ole Miss head coach Hugh Freeze said, per Hugh Kellenberger of the Clarion-Ledger. "But we turned it over and had negative plays. … Before you know it, it’s a different game."

Ole Miss' toothless performance against Florida should cause a huge fall from No. 3 in the polls. With one-loss Stanford routing Arizona and Notre Dame fighting back in a close loss against Clemson this week, this projection has the Rebels at No. 16, right in front of idle USC.

Notre Dame

You've got to hand it to Notre Dame. The Irish just don't quit, even when the odds are stacked against them.

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Notre Dame rallied to score 19 points in the fourth quarter at Clemson in a game that was played in dreadful weather conditions. But a pair of missed two-point conversions and four turnovers were too much for the Irish, who can take some positives away from their trip to Death Valley.

"When the torrential rain settles in South Carolina, No. 6 Notre Dame’s season is not lost, and the Irish could very well still find themselves in the playoff hunt as the season progresses," Bleacher Report's Mike Monaco wrote.

The Irish's failed comeback effort in rainy Clemson should be looked upon more favorably than Ole Miss' virtual no-show at Florida on Saturday night. Notre Dame won't take as big of a hit heading into Week 6.

UCLA and Georgia

UCLA was also the face of a late comeback attempt Saturday night, but the Bruins couldn't prevent Arizona State from scoring a back-breaking, game-sealing touchdown inside the Rose Bowl.

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The Bruins entered the fourth quarter down 29-10 and scored back-to-back touchdowns behind the backfield tandem of Josh Rosen and Paul Perkins. However, the decision to take an intentional safety didn't pay off, as a less than full-strength UCLA defense couldn't get Arizona State's offense off the field late.

Georgia, on the other hand, was completely outplayed in its home loss to Alabama, which entered the game in a much better position than Arizona State. The Bulldogs still have a good chance to take home the SEC East, but they'll have to rebound in a big way these coming weeks.

Both teams entered the week right beside each other in the polls, and their disappointing losses will stick them down in the lower reaches of the Top 20. With No. 20 Oklahoma State edging a Kansas State team that was forced to use yet another starting quarterback at home, they slide into No. 18 and No. 19.

Justin Ferguson is a college football writer at Bleacher Report. You can follow him on Twitter @JFergusonBR.