Bengals QB Andy Dalton and RB BenJarvus Green-Ellis left the field in San Diego on Sunday with their fourth win in a row after beating the Chargers 20-13. (US Presswire)

The era of Chargers coach Norv Turner may have been unofficially laid to rest on Sunday when the Cincinnati Bengals defeated host San Diego, 20-13, at Qualcomm Stadium.

The Chargers fell to 4-8, and their playoff hopes are all but gone. The Bengals improved to 7-5 and kept their playoff hopes alive with the road win, their fourth consecutive victory. Cincinnati is tied with the Steelers in the chase for the AFC's second wild-card berth.

The first quarter flew by with both teams possessing the ball just once. QB Andy Dalton methodically marched the Bengals down the field on an 18-play, 91-yard drive that consumed 7:21 of clock. TE Jermaine Gresham capped off the game’s opening possession with a 19-yard TD reception.

QB Philip Rivers nearly answered by putting together his own 12-play, 79-yard, 7:39 drive. The Bolts, however, had to settle for a 20-yard Nick Novak field goal.

With the opening TD, Dalton had thrown 10 TDs with no INTs over the last four games. That changed on the Bengals' next possession when Chargers ILB Demorrio Williams intercepted Dalton and returned the ball 31 yards for a pick-6.

For Williams, who received the start in place of Donald Butler (groin), it was his second INT return for a TD this season. It also marked the fifth pick-6 for the Chargers defense this season, second most in franchise history.

Dalton answered the mistake with another long drive that resulted in a 19-yard field goal from Bengals kicker Mike Nugent. That tied the game 10-10.

Rivers took San Diego on an 85-yard drive to end the half. The Bolts had a second TD opportunity slip away when RB Ronnie Brown made an 8-yard reception but was tackled on the 1-yard line. A timeout was called with one second remaining, and San Diego settled for a Novak field goal once again, this time from 19 yards to give the Chargers a 13-10 lead.

At that point, it appeared the game could develop into a high-scoring affair; the two offenses had combined for 428 yards at the break, the Bengals with 223, the Chargers with 205.

But this game was no different for the Chargers than many of the others, and the offense struggled in the second half -- even while the defense did its part in producing two turnovers.

SS Corey Lynch, who was playing for Atari Bigby (groin, IR), ended the Bengals' first third-quarter drive with an INT. Five plays later the Chargers punted.

Another missed opportunity for the Chargers came late in the third quarter when, after a sack and Rivers fumble lost nine yards and five more yards were shaved from a delay-of-game penalty, Novak attempted a 54-yard field goal and missed.

The Bengals finally took a 17-10 lead when Dalton scampered into the end zone on a 6-yard run early in the fourth quarter, and they held on for the victory.

Not since Week 9 of 2009 have the Chargers won or tied a game with a last possession TD, and nothing changed Sunday. Rivers drove the Chargers to the Bengals' 17-yard line before throwing three incompletions. His final pass was intended for WR Malcom Floyd, but it was intercepted by S Reggie Nelson in the end zone.

The win was the Bengals' first in California since 2003; they are now 2-4 in the Golden State under Marvin Lewis.

Turner blamed the Chargers' second-half struggles on an inability to get the ground game going. “We can’t run the ball right now,” Turner said. But it should be noted that he only called five running plays in the final 30 minutes.

RB Ryan Mathews had five attempts for 12 yards. Mathews finished with 12 carries for 26 yards (2.9 average). He said he would like to have more opportunities. “That’s me,” Mathews said. “But I will do whatever I can and whatever I’m asked for, for the team. Whether that’s two carries or 25 carries, no matter what it is.”

The O-line is beat up. LT Mike Harris (undrafted, UCLA) has been playing for Jared Gaither (groin, IR), and starting LG Tyronne Green (hamstring) and RT Jeromey Clary (knee) did not finish. “I don’t know that I’m going to look at the film and say Ryan had a lot of room to run,” Turner said.

When the game turned: Novak's 54-yard missed field goal.

Highlight moment: ILB Demorrio Williams' INT for a TD.

Top-shelf performances:

  • Bengals RB BenJarvus Green-Ellis rushed for 118 yards on 25 carries. He became the first Bengals RB to have a 100-yard plus performance in three straight games since Corey Dillon in 1999.

     
  • Chargers WR Danario Alexander had six receptions for 102 yards.

Head scratcher: Chargers fans booed on both short field-goal attempts, but both of them appeared to be the right call by Turner.

What they said:

  • Green-Ellis on the running game taking pressure off Dalton: “That’s what we want to do. We want to take some of the pressure off of Andy and A.J. [Green] so they don’t have to make plays every time we get the ball. When we can do that, it really helps the team out.”

     
  • Chargers FS Eric Weddle on the offense failing to score on final drive: “It’s deeply frustrating. Defense played their tails off tonight. We gave ourselves a chance, made a bunch of big plays, but it wasn’t enough. Defensively, we fought. We made a lot of plays, but it wasn’t enough in the end, so we just have to do more.”

     
  • ILB Demorrio Williams on his INT for a TD: “It was good play and all, but if you don’t come away with the win the play doesn’t really mean anything.”

QB Philip Rivers on the Chargers offensive failures: “We don’t want to be struggling; were trying not to be. . . .  We’re in a rut and all we can do is keep playing.

Injury update: San Diego -- RT Jeromey Clary (knee), WR Seyi Ajirotutu (hand), SS Corey Lynch (quad), LT Mike Harris (ankle) and C David Molk (thumb). Cincinnati -- CB Dre Kirkpatrick (concussion).

Going forward: Chargers -- They travel to Pittsburgh to play the Steelers (7-5) and have never won a regular season game in the steel city. Bengals -- They will host the Cowboys (5-6) in what is another near must-win for them to keep their surging playoff hopes alive.

Follow the Chargers and Dan McLellan on Twitter @CBSChargers and @sandiegosports.

Stay dialed in on the Cleveland Browns on Twitter at @CBSBrowns throughout the season with on-site updates from CBSSports.com RapidReports correspondent Marty Gitlin.