Harvey Unga ran for 113 yards and three touchdowns and No. 19 BYU converted two interceptions and a blocked punt into scores while holding off Colorado State 42-23 Saturday.
Max Hall passed for two touchdowns and ran for another as the Cougars (3-1) won the Mountain West Conference opener one week after getting blown out at home by Florida State.
The Cougars still had some defensive lapses in the second half, but built a 21-0 lead off Colorado State's mistakes in the first quarter.
Hall was 18 for 29 for 241 yards with two touchdowns and two interceptions.
Grant Stucker completed 30 of 50 passes for 372 yards and two touchdowns for the Rams (3-1, 0-1), whose six-game winning streak ended.
Colorado State got within 28-17 on a field goal early in the fourth quarter and answered Unga's third TD run with a 13-yard touchdown pass from Strucker to Tyson Liggett to make it 35-23 after the two-point conversion failed. But the Rams could not keep matching BYU to overcome the deficit.
Unga ran for 88 yards in the second half and became the first Cougars player to top 100 yards this season.
The Cougars led 21-0 after the first quarter, needing only a pair of plays on each drive to cover the short distances to the goal.
Colorado State receiver Rashaun Greer tipped both intercepted passes high enough that a defender was easily able to grab it. Brian Logan had the first, leading to Unga's 4-yard touchdown run barely two minutes into the game, then Andrew Rich grabbed the second at the Colorado State 39. Hall threw a 37-yard pass to O'Neill Chambers down the sideline, then Hall faked out everybody with a bootleg and trotted into the end zone with 3:04 left.
The Cougars got the ball right back when Matt Marshall blocked a punt and BYU went up 21-0 on Unga's 5-yard run with 25 seconds left in the first.
Hall's pass to McKay Jacobson for an apparent touchdown was overturned for pass interference called on Dennis Pitta. It was one of 10 BYU penalties called in the game, but Pitta redeemed himself on the next play with a diving catch on an 18-yard touchdown pass from Hall to put BYU up 28-7. It was the first time all day BYU was able to drive any distance, going 82 yards on 10 plays to get the margin back up to three touchdowns.