COSTA MESA, Calif. (AP) -- Deep in his 12th season as the Chargers' starting quarterback, Philip Rivers is playing some of his best football.

In his first game since turning 36 years old, Rivers carved up the Washington Redskins' secondary on the way to 319 yards and two touchdowns in Los Angeles' 30-13 victory Sunday.

That blowout win was just the latest big game in Rivers' string of savvy performances for the Chargers (7-6), who have won four straight heading into Saturday's showdown with Kansas City (7-6) for first place in the AFC West.

While the Chargers have an increasingly impressive defense and several offensive playmakers, the quarterback with the three-hour daily commute from San Diego is the engine driving them toward the postseason.

"We've been on a good little run the last few weeks," Chargers offensive coordinator Ken Whisenhunt said Monday. "A lot of it has to do with Philip and the way he's playing."

During the Chargers' winning streak, Rivers has 1,348 yards passing with eight touchdowns and four straight passer ratings over 100. He also hasn't committed a turnover during that four-game stretch, the longest turnover-free streak of his entire career.

"He's unstoppable," said receiver Tyrell Williams, who caught a beautiful 75-yard TD pass from Rivers on Sunday. "I don't even have a word for him. He's just playing great. I know he's going to keep doing what he's doing, and if he keeps playing like that, we're going to be a hard team to beat."

Not bad for a quarterback who threw a career-worst 21 interceptions last season and then wondered if the end of his Chargers career was near when they started 0-4 in their relocation season.

"(There were) a lot of different emotions," Rivers recalled Sunday. "A little bit of, `You've got to be kidding me! Could it be any worse right now? We moved up the road. We've lost four in a row. Is this my last 12 games here?' You have all of those thoughts."

Instead, the Chargers have won four straight home games while moving above .500 for the first time since September 2015.

The Chargers have given themselves the chance to be the first NFL team since the 1992 San Diego Chargers to make the playoffs after starting 0-4. A win in Kansas City would put the Chargers on an inside track to their first division title since 2009, the last of four straight AFC West champions led by LaDainian Tomlinson, Antonio Gates and Rivers.

"While it's been real exciting, we've been right here before on the cusp, and we lose the last two or three, and you end up a game out," Rivers said. "While everybody is excited and feeling pretty good about what we've done to get back in it, we've got to make sure nobody relaxes. … You hear all this positive stuff about the Chargers now, but we have to make sure we continue to move forward like we have been."

In some previous seasons in San Diego, Rivers and the Chargers got off to outstanding starts before fading down the stretch, either due to nagging injuries or slumping performances by a team that has made the playoffs once since 2009.

This season has been something different: Rivers completed just 63.3 percent of his passes and made five turnovers during the 0-4 start, only to improve steadily as the season progressed.

Rivers has moved up to fourth in the NFL with 3,611 yards passing, behind only Ben Roethlisberger, Tom Brady and Matthew Stafford. His 23 touchdown passes are fifth in the league, and he has thrown only seven interceptions all season -- just three in the past 10 games.

Most importantly, Rivers and his offense are playing with palpable confidence while winning seven of their past nine games overall. Rivers said he felt good about the Chargers' chances against the Redskins after just one look at their scripted plays for the start of the game.

Although he has never been the NFL's most nimble quarterback, Rivers has been remarkably adept at avoiding rushes and blitzes in recent weeks. He was sacked twice by the Redskins, but avoided trouble on several additional plays.

He didn't show that caution while leading the blocking for Travis Benjamin on a reverse running play in the second half, however. Although Rivers didn't end up hitting anybody, that play still sent shivers up the spines of Whisenhunt and head coach Anthony Lynn one day later.

"He looked like a parade master going down the field," Whisenhunt said. "I would have preferred if he had just gone ahead and run out of bounds so he could just get out of the action."

NOTES:Backup RB Andre Williams is probably out for the season due to surgery on his injured wrist. Lynn believes Williams was hurt on the final play against Washington. The Boston College product plays on special teams and has nine carries for 25 yards. Lynn expects Branden Oliver, who has played in just one game since Oct. 1, to step in.