SALT LAKE CITY — Backup quarterback Corbin Louks ran for 109 yards and two touchdowns and starter Brian Johnson threw two touchdown passes as No. 14 Utah remained unbeaten with a 49-16 win over Colorado State today.

The Utes improved to 8-0 for the fourth time ever and gained a season-high 549 yards of offense in Johnson's 21st win as a starter, tying Alex Smith's school record.

Utah (8-0, 4-0 Mountain West) caught Colorado State (3-4, 1-2) off guard by subbing the speedy Louks for Johnson periodically and he capitalized by taking two option keepers for touchdowns, including a 69-yard, zig-zagging run that put Utah up 49-16 with 9:30 left to play.

The Utes have been 8-0 only three other times — 1930, when they were perfect in an eight-game season, 1994, and 2004. The last of those teams went undefeated and played in the Fiesta Bowl, feats they're still in position to repeat.

Utah is off until playing at New Mexico on Nov. 1 and heads into the bye week with its best offensive game of the season. The Utes' previous high for offense was 461 yards against Utah State on Sept. 13 and they nearly beat that by 100 on Saturday.

Matt Asiata scored on two 3-yard runs and Johnson completed his first eight passes and finished 18-for-26 for 185 yards with one interception. Louks had five carries and completed his only pass, a 37-yarder. Jereme Brooks took a reverse 34 yards for a touchdown as the Utes outscored the Rams 21-3 in the second half.

Gartrell Johnson ran for 95 yards on 20 carries for Colorado State and Billy Farris was 19-for-33 for 166 yards with a touchdown that tied it at 7 in the first quarter.

Jason Smith kicked three field goals for Colorado State, including a 52-yarder that got the Rams within 28-16 midway through the third quarter.

The Rams were driving again, but Chaz Walker intercepted a pass from Farris at Utah's 49-yard line and Louks ran up the middle a few plays later for a 21-yard touchdown to put Utah up 35-16 with 2:20 left in the third quarter. Brooks added another score when he leaped over the goal line at the end of his reverse in the opening minute of the fourth quarter, then Louks capped the scoring with the run of the day.

Utah was at its own 31 and Louks kept it on the option, breaking free and heading for his own sideline. Colorado State just about had him inside the 25 yard line, but Louks cut back across the field and outran the Rams to the end zone.