AIR FORCE ACADEMY, Colo. _ Darrell Mack scored three second-half touchdowns, including a 9-yard run up the middle with 58 seconds remaining, to help No. 20 Utah rally for a 30-23 win over Air Force today.

The Utes are 4-0 for the first time since 2004, when they went 12-0 in Urban Meyer's last season with the team before he bolted for Florida.

Mack and Matt Asiata wore down Air Force, with the tailback tandem churning through the Falcons' defense, especially in the second half. Asiata finished with 19 carries for 116 yards, while Mack had 101 on 18 attempts.

Utah (4-0, 2-0 Mountain West Conference) kept Air Force's vaunted ground game in check, allowing just 53 yards. The Falcons (3-1, 1-1) entered the game with the second-best rushing offense in the nation, averaging 358 yards a game.

The Falcons got back into the game by discovering their passing game, something that was lacking in a win over Houston the week before when quarterback Shea Smith went 0-for-7. It was only the fifth time in school history the team didn't complete a pass.

But Smith completed a 37-yard pass to Kevin Fogler and then a 29-yarder to Josh Cousins, setting up Savier Stephens' 1-yard plunge with 5:06 remaining to tie the game at 23.

The Utes then marched the ball down the field, with Mack bursting through a seam in the Falcons' defense for the game-winning score.

Smith was intercepted by Utah safety Joe Dale to end the game.

Mack's 8-yard touchdown run early in the third quarter tied the game. He also had a 1-yard score on fourth down with 13:09 remaining that temporarily gave the Utes the lead.

Utah quarterback Brian Johnson had a first half he'd rather forget, fumbling twice and throwing an interception.

He rebounded to finish with 243 yards passing and one touchdown. He was also sacked five times.

Johnson was sacked by Rick Ricketts late in the second quarter, the ball squirting free. Jake Paulson picked it up and rumbled 25 yards for the touchdown, giving the Falcons a 16-9 lead at halftime.

Air Force had scored 2 minutes, 18 seconds earlier when Kyle Lumpkin hauled in an 8-yard touchdown pass from Smith. The touchdown was set up by a 42-yard catch by Fogler.

The Utes dominated the opening quarter, going up 9-0 on a 47-yard touchdown reception by David Reed down the left sideline, followed by a safety when Falcons punter Ryan Harrison fumbled the ball out of the end zone.

Air Force had minus-3 yards in the first 15 minutes.

Falcons safety Chris Thomas hounded Utah all afternoon, tipping a pass to teammate Reggie Rembert for an interception to thwart a drive, recovering a fumble and sacking Johnson.

Louie Sakoda, one of the top kickers in the nation, missed two field goals for Utah, a 48-yard attempt in the first half and a 54-yard try in the third.

Sakoda rescued Utah at Air Force in 2006, kicking a 37-yard field goal as time expired for a 17-14 win.