SAN FRANCISCO (AP) _ Compared to new coach Mike Singletary's feuding, fumbling, quarterback-switching 49ers, even the struggling Seattle Seahawks looked sharp.

Fullback Leonard Weaver made two lengthy touchdown catches, Josh Wilson returned an interception 75 yards for a score and the Seahawks ruined Singletary's tumultuous debut with San Francisco in a 34-13 victory today.

Seneca Wallace passed for 222 yards in his third career victory as a starter, including short passes turned into scores of 43 and 62 yards by his fleet-footed fullback. T.J. Duckett had an early 1-yard TD run as the Seahawks (2-5) calmly snapped their three-game losing streak and evened the season series with the Niners, who lost their fifth straight.

Seattle's steady effort was nothing like the crazy day for the 49ers (2-6) and Singletary, the Hall of Fame linebacker who took over the team after Mike Nolan was fired last Monday. In Singletary's first game in charge, he couldn't immediately fix a porous defense — but he benched quarterback J.T. O'Sullivan after three turnovers and ordered hotheaded tight end Vernon Davis off the field after a foolish penalty.

Before Singletary went into the 49ers' locker room after the game, he removed his hat and spoke to the fans above the tunnel, saying: "I apologize. I apologize to you guys. I apologize."

Wallace was uneventfully solid in his sixth career start in place of Matt Hasselbeck, who sat out another week with his back problems. Weaver, an unassuming third-year pro with just six previous catches this season, turned two simple passes into huge gains, romping past San Francisco's tacklers.

He scored both of Seattle's second-half touchdowns, including the clinching score on a 62-yard run down the Seahawks' sideline with 6:10 to play.

Singletary, known for his fiery motivational speeches, was promoted from assistant head coach to replace Nolan, who went 18-37. The Niners came out with little passion early — and thanks mostly to O'Sullivan's mistakes, the Seahawks had a 20-3 halftime lead with just 111 yards of offense.

Shaun Hill replaced O'Sullivan right before halftime, finishing with 173 yards passing and a TD throw to Jason Hill. Frank Gore rushed for 94 yards and caught seven passes for 65 more, but San Francisco nearly came apart at the seams heading into its bye week.

O'Sullivan fumbled on San Francisco's first two possessions — bringing his NFL-leading total to 11 — and threw that crushing interception to Wilson in the final minute of the first half before getting benched in favor of Hill, the longtime backup who led the 49ers to two wins late last season.

After Davis caught a 7-yard pass late in the third quarter, he slapped a Seahawks defender's head after the tackle for a 15-yard personal foul. Singletary pulled Davis from the game and yelled at the former No. 6 overall pick in full view of his teammates, commanding Davis to sit on the bench — and then ordering him to the locker room at the next timeout.

Davis waved his helmet at the crowd as he left, although Candlestick Park had thousands of empty seats.