In the 66-year history of the preseason AP poll, only nine teams have finished No. 1 without being ranked at the season's start in the Top 15. Here's the last five national champion teams to pull it off.

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2010 Auburn

Preseason: No. 22

Gene Chizik entered his second year as the Tigers' coach after a respectable 8-5 season, but 3-5 SEC mark. Cam Newton, the new QB, was a junior college transfer and former Florida backup. In-state rival Alabama had just won its first title under Nick Saban and was an overwhelming pick to repeat. Other than the War Eagle faithful, no one thought the Tigers would upset the Tide, let alone end up No. 1. But Newton would rule the year, winning the Heisman, going undefeated and landing the top pick in the NFL draft.

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2000 Oklahoma

Preseason: No. 19

Bob Stoops was back for his second season as coach after leading OU to its first bowl game in four years, but poll voters thought he had more work to do before bringing the Sooners back into contention. Obviously, they were wrong. After easily sweeping through its non-conference schedule and Big 12 opener against Kansas, Oklahoma broke into the Top 10 before beating No. 11 Texas, No. 2 Kansas State and No. 1 Nebraska. After that run, they were voted No. 1 on Oct. 30 and finished the year with one of the most impressive defensive performances in a national title game, shutting down Florida State 13-2.

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1984 BYU

Preseason: Unranked

Back then, the AP poll included only 20 teams instead of 25. BYU had closed out the previous year with 11 straight wins and ended No. 7, but still didn't make the cut for the preseason poll. An upset of No. 3 Pitt in season opener put them right back in the poll. The Cougars would go on to be the nation's undefeated team, capping the year with a 24-17 win over unranked Michigan in the Holiday Bowl.

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1983 Miami

Preseason: Unranked

Miami was 7-4 the past year and opened the 1983 season with a 28-3 loss to Florida. They were not part of any national title talk. Then they recovered with resounding wins in their next eight games, including a 20-0 upset of No. 13 Notre Dame and 20-3 over No. 12 West Virginia. They earned a bid to their hometown Orange Bowl to play perennial power and top-ranked Nebraska. Considered one of the greatest games in college football history, the Huskers scored a TD with 48 seconds left, putting them within a point of Miami. Nebraska coach Tom Osborne went for a two-point conversion and the win, rather than kick for a tie and still quite possibly the national title. A missed pass on the conversion attempt led to Miami's first No. 1 finish.

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1981 Clemson

Preseason: Unranked

Danny Ford's Clemson team was coming off a 6-5 season. The Tigers wouldn't enter the AP poll until they upset defending national champion Georgia 13-3 in their third game of the season. From there, they'd keep winning and climbing the rankings. They didn't reach No. 1 until the season's final poll, after beating No. 4 Nebraska 22-15 in the Orange Bowl.