Tanner Mangum put up bigger numbers, but Josh Rosen escaped with the win in a battle between two of the nation’s most promising young quarterbacks.

Junior running back Paul Perkins had a monster game to help 10th-ranked UCLA to a 24-23 victory over No. 19 BYU on Saturday night at the Rose Bowl in Pasadena, Calif.

Perkins carried 26 times for a career-high 219 yards and one touchdown for the Bruins (1-0), who rallied from a 10-point deficit in the fourth quarter.

"We had to overcome a lot to win that game tonight -- a lot of adversity," UCLA coach Jim Mora said. "It starts with a very good BYU team that played physical and tough and gave us all we could handle."

Rosen completed just 11 of 23 passes for 106 yards with one touchdown and three interceptions. He was outdone by Mangum, who completed 30 of 47 passes for 244 yards and one touchdown for the Cougars (2-1).

Senior running back Adam Hine rushed for a career-high 149 yards and one touchdown on 23 carries for BYU, which let the lead slip away in the final minutes.

Junior linebacker Harvey Langi played both ways for the Cougars. He had a team-high eight tackles and the first two interceptions of his career. On offense, he carried the ball twice, rushing for two first downs.

The Cougars jumped out to a 7-0 lead after Hine scored on a 7-yard run with 9:39 to play in the opening quarter. His touchdown capped an 11-play, 71-yard drive on BYU's first possession.

The Bruins cut the deficit to 7-3 when Ka'imi Fairbairn kicked a 35-yard field goal early in the second quarter. The Cougars answered with a field goal of their own, extending the lead to 10-3 on a 40-yarder by Trevor Samson with 9:18 remaining in the first half.

UCLA tied the score at 10 on a 5-yard run by Perkins with 9:27 to go in the third quarter. BYU answered quickly, going up 17-10 on a 14-yard touchdown pass from Mangum to senior wide receiver Mitch Matthews with 6:26 to go in the third quarter.

Matthews, who has caught a pass in 27 consecutive games, had team highs of nine receptions and 84 yards.

The Cougars extended their lead to 20-10 on a 45-yard field goal by Samson early in the fourth quarter, but the Bruins battled back. They cut the deficit to 20-17 on a 19-yard touchdown pass from Rosen to senior wide receiver Jordan Payton with 12:16 remaining, capping a five-play, 68-yard drive.

BYU went up 23-17 on a 32-yard field goal by Samson with 5:39 to go, but the Bruins mounted a seven-play, 80-yard drive to take their first lead of the game on a 3-yard run by sophomore running back Nate Starks with 3:21 to play.

Starks had runs of 31 and 22 yards on the drive, finishing with a career-high 81 yards on seven carries.

BYU amassed 405 yards of total offense. UCLA had 402. The Cougars dominated time of possession but managed to score only three points off three UCLA turnovers.

The Bruins won despite going just 1 of 9 on third-down conversions.

Rosen's struggles were somewhat surprising. He completed 28 of 35 passes for 351 yards and three touchdowns in a season-opening victory over Virginia and for 223 yards on 22-of-42 passing last week in a win over UNLV.

Mangum has enjoyed quite a start to his college career, too.

He replaced injured starter Taysom Hill early in the fourth quarter of the season opener against Nebraska and rallied his team to a 33-28 victory. He completed 7 of 11 passes for 111 yards, including a 42-yard touchdown pass on the final play of the game. He followed that with 309 yards on 17-of-28 passing in last week's 35-24 victory over Boise State.

Mangum had an opportunity to produce another magical moment against UCLA, but the Bruins wouldn't allow it. BYU was facing a fourth-and-7 from midfield with just over one minute remaining when UCLA linebacker Myles Jack intercepted Mangum's last pass to seal the victory.

"They had a great pass rush and we were outside the pocket," BYU coach Bronco Mendenhall said. "Tanner tried to stay alive as long as possible and the receiver was working to get open. Their defender made a great play."

The Bruins have won 14 of their last 15 nonconference games, including 11 in a row since a loss to Baylor in the 2012 Holiday Bowl. They are 12-0 in regular-season nonconference games in four seasons under Mora.

UCLA will play its Pac-12 Conference opener against Arizona next weekend in Tucson, Ariz. BYU will visit Michigan.

NOTES: UCLA faced BYU for the first time since 2008 when the then-18th-ranked Cougars crushed the Bruins 59-0 in Provo, Utah. ... The Bruins and Cougars are scheduled to meet again next season in Provo, Utah. ... This is the third consecutive season in which UCLA has been ranked in the top 10. ... The last time BYU defeated a top-10 team was in 2009 when the Cougars upset No. 3 Oklahoma.