SAN FRANCISCO — Mike Singletary put his stamp on his coaching debut for the San Francisco 49ers, benching turnover-prone quarterback J.T. O'Sullivan in the second quarter and then sending volatile tight end Vernon Davis to the locker room with more than 10 minutes remaining Sunday.

"I told him that he would do a better job for us right now taking a shower and coming back and watching the game than going out on the field," Singletary said after the 34-13 loss to Seattle. "Simple as that."

The confrontation with Davis started after Davis was called for an unnecessary roughness penalty for slapping a Seahawks defender's head after a tackle on a 7-yard reception in the third quarter.

Davis tried to avoid his coach as he ran to the sideline but Singletary got in his face and gave him an earful before sending him to the bench. Singletary said he was upset by what he considered a nonchalant attitude by Davis, who did not seem to understand why his coach was so upset.

Singletary later walked over to talk to Davis on the bench, yelling some more at the former No. 6 overall pick in full view of his teammates. Then with 10:41 remaining in the game, Singletary went back to Davis and told him to go to the locker room. Davis started walking before being called back to get his helmet. He then waved his helmet at the crowd as he left.

"I'd rather play with 10 people and just get penalized all the way until we have to do something else rather than play with 11 when I know that right now that person is not sold out to be a part of this team," Singletary said. "It is more about them than it is about the team. Cannot play with them, cannot win with them, cannot coach with them. Can't do it. I want winners. I want people that want to win."

Former coach Mike Nolan pulled Davis out of a game earlier this year but did not send Davis to the locker room. Last month at New Orleans, Davis made a 19-yard catch with 6:20 remaining for his only reception in a 31-17 loss and pounded his chest and yelled loudly.

Davis came to San Francisco with much hype after being drafted sixth overall in 2006. But he has failed to live up to expectations, making just 72 catches his first two seasons. He had four catches for 29 yards Sunday, giving him 16 receptions for 196 yards in eight games this season.

Davis was unavailable for comment after the game. Davis wanted to talk to his coach, but Singletary advised against it.

"I told him he did not want to talk to me," Singletary said. "I assured him, 'You do not want to talk to me right now.'"

In the second quarter, Singletary benched O'Sullivan after he threw an interception that was returned by Josh Wilson 75 yards for a touchdown. That was O'Sullivan's second turnover of the game and 17th of the season.

Shaun Hill, who won his only two career starts last season, played the rest of the way, going 15-for-23 for 173 yards, a touchdown and no turnovers.

Singletary said he would wait before deciding whether O'Sullivan and Davis would get their starting jobs back after the bye week.