Backups Tim Rattay and Ken Dorsey will play the remainder of the game.
SANTA CLARA, Calif. (AP) -- The San Francisco 49ers are ready to see what Alex Smith can do.
The NFL's top draft pick will be the 49ers' starting quarterback in their preseason opener against the Oakland Raiders, coach Mike Nolan said Wednesday.
Smith earned the honor with his impressive work in training camp, where he has practiced with the 49ers' first-team offense since the opening workouts.
Smith took the news with the same poise he's shown against every challenge in the last year, when he went from relative obscurity at Utah to the top of the draft class with one spectacular college season.
He'll soon find out whether he can keep that cool with Warren Sapp and Charles Woodson chasing him at Candlestick Park on Saturday.
"This is a big opportunity, but it's still just a preseason game, and I have to treat it that way," Smith said. "The atmosphere will be nice. It will be realistic. It's one more thing for me to learn."
Smith will take about 25 snaps before giving way to Tim Rattay, who started nine games last season while battling several injuries during his only campaign as San Francisco's No. 1 quarterback.
Ken Dorsey, who started seven games last season, will play the remainder of the exhibition.
Smith has been solid in camp, making crisp throws and eagerly soaking up the 49ers' new West Coast offense. He signed a contract with San Francisco four days before the start of training camp, avoiding any chance of a holdout that could limit his schooling.
So Nolan saw no reason to change the player rotation established early in camp.
"It's certainly a welcome to the NFL," Nolan said. "I want to see how he operates under the pressure. It's a rivalry ... and I want to see how he responds to that. We're looking for someone to take that position, and he's got a chance."
Nolan repeatedly has said he hoped Smith would win the starting job for many reasons, including the 49ers' financial commitment to the 21-year-old passer. Though Smith will start against Oakland, Nolan said the competition with Rattay and Dorsey isn't over.
"I've just got to keep going out there and get better," said Rattay, Jeff Garcia's backup for three seasons before becoming the starter last year. "I feel good about the way I've been practicing. I understood it was going to be a competitive situation, and I love to compete."
Nolan has no qualms about whether he's rushing his prize quarterback into competition too early. Though Pittsburgh's Ben Roethlisberger joined a much better team last fall when he became a rookie star, Nolan sees much to learn from the Steelers' treatment of their young passer.
"What they did was, they kept it simple," Nolan said. "That [simplicity] was a great fit for the quarterback, and that's in our offense in the West Coast, too."
Nolan also sees little point in putting the league's top pick on the shelf for a season of schooling, as the Cincinnati Bengals did with Carson Palmer in 2003.
"There's not much to learn from that situation, because he didn't play," Nolan said. "And after watching [Palmer] last year, it's hard to see why he didn't."
The Raiders' defense is sure to be eager to crush the rookie, who signed a $49.5 million contract last month. The 49ers' offensive line also is patchwork, with four-fifths of the projected starting lineup -- center Jeremy Newberry, left tackle Jonas Jennings, left guard Justin Smiley and rookie right guard David Baas -- likely to miss the game with injuries.
But Smith, who ran with the ball fearlessly while leading the Utes to an undefeated season last fall, is as ready as he can be.
"I'm sure I'll present a nice target for them, but I didn't expect anything else," Smith said. "That's why we have pads."