SANTA CLARA, Calif. -- Mike Singletary isn't worried about his job security following the San Francisco 49ers' 0-4 start. In fact, he says it's the furthest thing from his mind.
Singletary insists there's too much other stuff to get done than be concerned about his future with the franchise. He has two years remaining on the four-year contract he signed after the 2008 season, when he led the Niners to a 5-4 record after taking over on an interim basis for the fired Mike Nolan.
Team and league sources told ESPN NFL Insider Adam Schefter that Singletary's job is safe for now, however there are no assurances that Singletary would return after this season even though he has two years remaining on his contract after 2010.
If San Francisco doesn't win soon and turn around this surprising winless start, he understands he could become the fall guy. The Niners lost 16-14 on a last-second field goal at Atlanta on Sunday after jumping out to a 14-0 lead.
"It's the nature of this game," Singletary said Monday. "Players have responsibilities and if they don't do their jobs certain things happen. Coaches have responsibilities and if they don't do their job, things happen. My mind doesn't focus like that. I don't worry about who I need to talk to, am I OK? These 53 guys, that's my responsibility. You go out there on Sunday, you do your job. You win football games."
Except, so far, the 49ers can't find a way to win. Just when they looked headed for their first victory Sunday, cornerback Nate Clements fumbled after making a key interception. Atlanta answered with the winning drive.
"It definitely stung," Clements said. "I made a great read on the play. I've just got to hold that thing high and tight."
For a team so convinced it was playoff ready, the winless 49ers are in a serious hole with questions on both sides of the ball. Two main issues: struggling quarterback Alex Smith and safety Michael Lewis. San Francisco is 0-4 for the first time since going 2-14 in 2004.
Lewis didn't show up for Friday's practice or make the road trip after being told he was losing his starting job. The 49ers said Monday that Lewis had been released.
Lewis, who will be replaced on the starting defense by rookie Taylor Mays, is the third player to leave the team this year. Defensive lineman Kentwan Balmer was a no-show during training camp and was eventually traded to Seattle. Second-year running back Glen Coffee quit football to focus on his ministry.
Now, the 49ers must put all the distractions and mistake-filled play aside and try to get things in order for a Sunday night home game against the Philadelphia Eagles (2-2).
"We're right there, we're rolling, just little nicks and knacks we've got to get going on," second-year receiver Michael Crabtree said. "You can practice it all day but when game time comes you just got to do it and eliminate these turnovers."
In his first game under new offensive coordinator Mike Johnson, Smith completed 21 of 32 passes for 188 yards with one touchdown and two interceptions. He was sacked once. Smith did get more in sync with Crabtree, who made five catches for 58 yards.
San Francisco lost tight end Delanie Walker to a left ankle injury. He was on crutches and wearing a walking boot Monday.
Smith is trying to move forward and forget the frustration of the first four weeks. He has a 66.1 quarterback rating so far.
"I think everyone knows it's a long season, it's a marathon," he said. "A lot can happen. You have to keep your focus now and we're going to go over this game, learn from it. There's a big game this week and we have to prepare for it. I think we have great character, I think this locker room has great character. We have a lot of maturity."
Singletary is still standing by Smith 100 percent and expects him to become more consistent. The coach still believes he has a playoff team, too.
The Niners have two straight home games at Candlestick Park, a trip to Carolina and then their game with the Denver Broncos in London on Oct. 31 followed by the bye week.
San Francisco also has five remaining games against NFC West opponents.
"My high hopes, they haven't gone anywhere," Singletary said. "We're 0-4 but we have a lot of football games to play. The way our team's playing, I'm very encouraged by what I see. I'm very encouraged by what I hear our guys talking about and where their focus is. This is what I do. This for me right now is the time when you have to take it to the next gear. The last thing I'm doing is sitting around thinking: 'Oh man, I've got these problems. I got this, I got that.' I'm thankful that I have problems to deal with. If I've got an issue, if I've got a problem, that lets me know that I've got to work through something and there's an opportunity on the other side to get better."
Information from The Associated Press contributed to this story.