The previous three teams that won the national championship finished the season with at least one loss.

Neither No. 1 Florida nor No. 2 Alabama can afford to suffer its first loss of the season Saturday and still expect to play in the BCS National Championship Game.

With the winner heading to Pasadena, Calif., to play for the national title, Saturday’s Southeastern Conference Championship Game in Atlanta will have the feel of a national championship semifinal.

The Gators and Crimson Tide are No. 1 and No. 2 in the BCS rankings and were ranked first and fifth, respectively, in the preseason AP poll.

UF coach Urban Meyer has already been to two SEC Championship Games and two BCS National Championship Games as a Gator, but he said he couldn’t think of a bigger game that he has been a part of than the upcoming one.

“Now that we’re here, I can feel (the national championship-like atmosphere),” Meyer said. “People were trying to make it that type of game back in September. I think if I remember right, both teams were picked to make it to the championship game.”

The matchup was set after Alabama’s 24-15 victory over LSU on Nov. 7, but the talk of a rematch of last year’s SEC Championship Game started soon after the last one finished.

Both teams had key players depart after last season, mostly on the offensive side of the ball.

Florida lost the services of wide receivers Percy Harvin and Louis Murphy, and Alabama no longer has quarterback John Parker Wilson, running back Glen Coffee or left tackle Andre Smith. The Gators returned all of their starters on defense, and the Crimson Tide brought back nine of their 11 before losing star linebacker Dont’a Hightower to a knee injury early this year.

The experience of the defenses has been obvious as both units have dominated opposing teams most of the season.

Alabama’s and Florida’s defenses are ranked in the top eight in the nation in total, scoring, rushing and passing defense.

The most points either team let up in a game was the 24 Alabama allowed Virginia Tech to score, and the most UF has given up was 20 to Arkansas.

The two units have different styles of play, but they still share certain traits of a great defense.

“There’s a lot of similarities, both great defenses. There are similarities with our defense. A lot of team speed,” quarterback Tim Tebow said. “They run for the ball, make big plays.”

Despite finishing the regular season undefeated, neither team’s season was without drama.

Alabama trailed heading into the fourth quarter in three games this season and was leading by no more than seven points when the last quarter began in two other games, including a 12-10 win over Tennessee that needed two blocked field-goal attempts by nose guard Terrence Cody.

Florida never entered the fourth quarter trailing in any game this season, but four games were within a touchdown at the start of the final period, including a 23-20 win over Arkansas that required a 27-yard field goal by Caleb Sturgis.

The Gators also dealt with a new off-the-field storyline almost every week and have another one this week with the recent arrest and suspension of starting defensive end Carlos Dunlap.

Junior cornerback Joe Haden said the goal was not to go undefeated but to get to the SEC Championship Game because Meyer did not want the team to feel like the season was a failure if they lost a game early on. While both teams’ goal was not to finish undefeated but win a championship, they will now have to finish without a blemish to accomplish that aspiration.

“If you lose a game, then was the season a failure? He didn’t want that to be the case,” Haden said. “Now we’re sitting here undefeated. SEC Championship, we win this, we go on to the national championship.”