Dean Michaels

Alex Smith threw the go-ahead touchdown pass in the third quarter and David Akers added an insurance field goal as the San Francisco 49ers grabbed solo lead in the NFC West with a 13-6 triumph over the Seattle Seahawks Thursday at Candlestick Park.

With their fourth straight win against the Seahawks, the 49ers stormed ahead of the Arizona Cardinals (4-2) for the NFC West lead with a 5-2 record while Seattle dropped to third with a 4-3 mark.

Smith went 5-for-5 for 58 yards during the only touchdown-scoring drive, which he capped with a 12-yard heave to tight end Delanie Walker that staked the 49ers to a 10-6 lead in the third period.

"We finally got into a rhythm," said Smith, who completed 14 of 23 passes for 141 yards with one interception. "Mixing run and pass, moving the chains, obviously took some check-downs there in the second half with backs getting out.

Running back Frank Gore compensated for Smith's lack of passing yardage with 132 ground yards on 16 carries or an average of 8.2 yards per carry. He also led the 49ers in receiving yards with 51 yards on five receptions.

"I point to the physical play of our offensive line," 49ers coach Jim Harbaugh said. "Coming off the ball there were some big holes. Frank ran well, receivers were blocking. It was just that kind of physical play, some good plays were called and guys were feeling it and coming off the ball."

Seahawks playmaker Russell Wilson completed just 9 of 23 throws for a measly 122 yards with no touchdown while kicker Steven Hauschka provided the points for Seattle with two first-half field goals.

Wilson completed his first three passes for 32 yards in a 10-play, 62-yard drive that ended with a 52-yard field goal by Hauschka.

In retaliation, the 49ers drove 60 yards in 11 plays capped by a 38-yard field goal by Akers with 26 seconds left to tie the count at three.

The Seahawks started the second quarter with an eight-play, 63-yard drive that resulted in a 35-yard field goal by Hauschka for a 6-3 lead.

The 49ers stepped on the gas in the third period when Smith orchestrated a 10-play, 86-yard drive that he himself capped with a 12-yard scoring heave to Walker. During that drive, Gore touched the ball eight times for 49 yards.

The Seahawks tried to answer but Wilson's second-down pass to Braylon Edwards was intercepted by Pro Bowl free safety Dashon Goldson at the 49ers' 26-yard line.

"That was the most physical 30 minutes of football in the second half that I've ever seen our team play," Harbaugh said of the 49ers second-half play. "Really pleased - the way we covered kicks all night -- the way we played defense, the way we played offense, the way we moved people up front."

Alex Smith and David Akers Lead 49ers Past Seahawks - NFL 2012 Week 6