NEW ORLEANS — More often than not, when teams from so-called midmajor conferences face a reckoning in Bowl Championship Series games, they prove their brand of football is not so inferior.

No. 7 Utah of the Mountain West Conference capped a perfect 13-0 season with an upset of No. 4 Alabama of the Southeastern Conference, 31-17, in the Sugar Bowl on Friday night. It was the third time in four tries that a team from outside the major conferences has won a BCS bowl game.

Brian Johnson, Utah's senior quarterback, completed 27 of 41 passes for 336 yards and three touchdowns. Freddie Brown caught 12 of those passes for 125 yards in front of 71,872 in the Superdome.

Without two starting offensive linemen, Alabama's usually vaunted running game managed only 31 yards.

Tucked into a corner of the Superdome, Utah's fans exulted in the upset in their bright red shirts while the numb Crimson Tide fans started disappearing into the exits with five minutes remaining.

Utah was the original BCS Buster, crashing through a barrier after the 2004 season to beat Pittsburgh of the Big East in the Fiesta Bowl and finish 12-0. Ever since, the midmajor conferences have clamored for an automatic BCS berth.

Utah's players were mindful of the comments by Alabama coach Nick Saban, who said the Crimson Tide was the only team from a "real" B.C.S. conference to go undefeated in its league's regular season.

Alabama started the game without its All-America left tackle, Andre Smith, who was suspended for the game, but not many people thought the Crimson Tide would need Smith. The Tide, which was a 10-point favorite, still had a stingy defense and a depth of talent that comes with playing in the SEC.

Then, in a breathless first possession, Utah gashed the Alabama defense in 1 minute 19 seconds with a no-huddle offense and set the tone. The Utes went 68 yards in five plays. Johnson completed 5 of 5 passes in the drive as his receivers won one-on-one matchups out of the spread offense. Receivers Bradon Godfrey, who is 6 feet 3 inches, and Freddie Brown, who is 6-4, brushed off the smaller Alabama defensive backs to snare short pass after short pass.

Johnson finished the drive with a 7-yard touchdown pass to wide receiver Brent Casteel. Louie Sakoda's extra-point kick made the score 7-0, and the Alabama fans looked as stunned as their team.

When John Parker Wilson, the Crimson Tide quarterback, threw an interception on the next Alabama possession, Utah struck again. On third down, Johnson completed a 30-yard pass to wide receiver David Reed, who outjumped the fifth defensive back of the Tide, Marquis Johnson, at the 2-yard line.

On second down from the Alabama 2, the Utes showed they were serious. Alabama's Terrence Cody, a 6-5, 365-pound nose tackle, was buried at the point of attack as Utah running back Matt Asiata bashed into the end zone.