Smith to start against Colts

SAN FRANCISCO — Overall No. 1 draft pick Alex Smith was promoted to be the San Francisco 49ers' starting quarterback on Tuesday, ascending to the job after just four games as Tim Rattay's backup.

Smith will make his first NFL start on Sunday against Peyton Manning and the Indianapolis Colts at Candlestick Park. The former Utah star played in two of the 49ers' first four games, mopping up in losses to Philadelphia and Arizona.

"I feel that Alex gives us the best chance to win, and I believe he's ready," San Francisco coach Mike Nolan said. "Tim has handled everything very well, but at this time in the process, I believe it's time to get Alex in the game. . . . At 1-3, we didn't draft Alex to just sit him on the bench. At 1-3, I believe we need to begin to utilize him."

Rattay completed 57.7 percent of his passes this season for 677 yards, five touchdowns and six interceptions. He compiled impressive statistics in a season-opening win over St. Louis and a last-minute loss to Dallas.

But the 49ers' offense has been mostly terrible, with stark deficiencies in time of possession, total yards (1,989-995) and points (132-76) — and Rattay has been shaky and indecisive in the fourth quarter, when San Francisco has been outscored 48-0.

The 49ers managed just 168 total yards in last Sunday's 31-14 loss to Arizona in Mexico City. San Francisco's offense was shut out by the Cardinals, though Smith went 6-of-10 — his first NFL completions — for 34 yards after Rattay was pulled in the fourth quarter.

Smith was the 49ers' starter in their first two exhibition games, but he struggled to move the offense. His throws frequently were hurried and inaccurate, and he still was learning the intricacies of the West Coast offense.

Nolan gave the starting job to Rattay, Jeff Garcia's longtime backup who had an impressive preseason. The seventh-round draft pick started nine games in 2004 while recovering from three injuries.

At the time, Nolan said it was important not to be "wishy-washy" with the decision so Rattay could play without fear. But after three straight dismal performances by San Francisco's offense, Nolan made a change anyway.

Though Smith was a second-stringer in September, he got nearly as much practice time as Rattay. The natural zip on Smith's practice throws is obvious, and his mobility as a former spread-option quarterback with the Utes is something Rattay can't match.