CORVALLIS, Ore. — Oregon State's defense helped out when quarterback Cody Vaz struggled in the rain, and the No. 8 Beavers remained undefeated with a 21-7 victory over Utah on Saturday night that gave them their best start in more than a century.

Vaz made his debut last weekend as Oregon State's starter and threw for three touchdowns against Brigham Young to earn Pac-12 player of the week honors. This time, he passed for 174 yards against the Utes. But the Beavers' defense had an interception and a fumble recovery that led to two first-half touchdown runs by Storm Woods.

Woods had 17 carries for 46 yards and all three touchdowns for Oregon State (6-0, 4-0 Pac-12), which hadn't opened a season 6-0 since 1907, when the school was the Oregon Agricultural College.

Freshman Travis Wilson threw for 172 yards and a touchdown for Utah (2-5, 0-4), which opened conference play with four consecutive losses for the second straight season.

Vaz started a second consecutive game in place of Sean Mannion, who had surgery to repair a torn meniscus on Oct. 10. Mannion is already back at practice and was Vaz's backup.

OrSt — Woods 1 run (Romaine kick), :57.

Second Quarter

OrSt — Woods 2 run (Romaine kick), 14:27.

Utah — Murphy 18 pass from Wilson (Petersen kick), 6:00.

Fourth Quarter

OrSt — Woods 2 run (Romaine kick), 7:41.

A — 45,769.

Rushing — Utah, J.White 20-68, York 10-52, Dunn 2-25, D.Anderson 3-10, Christopher 1-(- 7), Wilson 9-(- 13). Oregon St., Woods 17-46, Cooks 2-10, Agnew 2-2, Wheaton 2-2, Vaz 2-(- 3), Team 3-(- 5).

Passing — Utah, Wilson 15-28-2-172. Oregon St., Vaz 16-26-0-174.

Receiving — Utah, Murphy 4-42, Scott 4-40, Matthews 2-41, J.White 2-24, Denham 1-14, Tonga 1-10, Dunn 1-1. Oregon St., Wheaton 7-90, Woods 3-20, K.Cummings 2-32, Anderson 2-12, Hamlett 1-12, Cooks 1-8.