Oregon State coach Mike Riley was right: There was no reason to worry about QB Cody Vaz

Moments after Cody Vaz's first-ever drive as starting quarterback for Oregon State, the Internet was humming.

"VAZzle-Dazzle," ''VAZ-tacular" and "VAZ-matazz" were among the nicknames that were bandied about. "Cody Vaz" was trending on Twitter.

Vaz, making his first start since high school, threw for 332 yards and three touchdowns in No. 8 Oregon State's 42-24 victory over BYU on Saturday. He completed 20 of 32 passes.

The 6-foot-1 junior, who took over for injured quarterback Sean Mannion, was named a Pac-12 player of the week on Monday.

"I don't think anybody in our locker room was particularly surprised Cody played well," coach Mike Riley said. "I think they've had faith in him as a teammate for a long time."

In addition to a cool 59-yard completion to Brandin Cooks, and another steady 29-yarder to tight end Connor Hamlett, Vaz made a block on a BYU defensive lineman that paved the way for Markus Wheaton to score on a 12-yard fourth-quarter reverse that bumped Oregon State's lead to 11 points.

Vaz was a pro throughout the game, and even gave the rest of the team a pep talk to start the fourth quarter.

"I just said 'The fourth quarter's our quarter,' ... I just wanted to get everybody pumped up a little bit," Vaz said.

Now there's talk of "Beavers BelieVAZ" T-shirts.

Before Saturday's start, Vaz had appeared in only five games for the Beavers, completing six of 17 passes for 48 yards. He had not played in a live game since 2010.

The victory over BYU moved the Beavers to 5-0 to open the season, their best start since 1939. Vaz's performance was just the latest surprise in an unexpected season for Oregon State, which went just 3-9 last year.

Mannion's injury was also a surprise, even to Riley. The 6-foot-5 sophomore was hurt on a handoff in the Beavers' 19-6 victory over Washington State the week before, but he never left the game and finished with 270 yards passing and a touchdown.

Two days later, the Beavers got word Mannion would need surgery to repair the meniscus in his left knee. He had surgery last week and is out indefinitely, although he could return before the end of the regular season.

Mannion was averaging 339.5 yards passing a game, then second in the Pac-12 and sixth in the nation. He has thrown for 1,358 yards with seven touchdowns and four interceptions this season. He is sixth on Oregon State's career list with 4,686 yards.

Last season as a redshirt freshman, Mannion unseated junior starter Ryan Katz, who had started the 2010 season for the Beavers. Katz has since transferred to San Diego State — making Vaz the backup this season.

Vaz grew up in Lodi, Calif., and played at St. Mary's High School, where he was 24-5 in two seasons as the starter. He was the Stockton Record's player of the year his senior season.

But he had played a supporting role until last Saturday. The Beavers, who are 3-0 in Pac-12 play, host Utah this Saturday night at Reser Stadium.

"It's just a great sign of a guy staying ready over a long period of time and it's part of the identity of our football team," Riley said. "Guys are getting ready to play and when called upon they go in and do the job."