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SAN DIEGO -- Andy Dalton and the Cincinnati Bengals didn't flinch.

No, all they had to do was bide their time and wait for the San Diego Chargers to cough up another fourth-quarter lead.

Dalton scrambled up the middle for a 6-yard touchdown with 4:11 left for the go-ahead score, and the Bengals won their fourth straight game, 20-13 over the punchless San Diego Chargers on Sunday.

The Bengals also kept coming after Philip Rivers, forcing two turnovers in the final 3:54.

"We kept overcoming adversity and we didn't flinch," coach Marvin Lewis said. "We just went out there and went back to work. ... We weren't perfect. But we had to keep playing and make adjustments and keep coming."

The Bengals (7-5) remained tied with Pittsburgh in the race for the AFC's second wild-card berth. The Steelers and Bengals are two games behind the AFC North-leading Baltimore Ravens, who lost to Pittsburgh.

The Chargers (4-8) lost their fourth straight game and for the seventh time in eight games. They remain mathematically, but not realistically, alive in the wild-card chase.

The Chargers are on the cusp of missing the playoffs for the third straight season, which is all but certain to cost coach Norv Turner his job, and it could get general manager A.J. Smith fired, as well.

With four games left in Turner's sixth season as coach, the Chargers are assured of their third non-winning season in the past five years. They were 8-8 last season and in 2008.

Denver clinched the AFC West title with a 31-23 victory against Tampa Bay. The Broncos haven't lost since overcoming a 24-0 deficit at halftime at San Diego on Oct. 15 to beat the Chargers 35-24.

The Chargers were shut out in the second half after taking a 13-10 halftime lead. They didn't score an offensive touchdown for the third time this season.

Trailing 13-10, the Bengals started the winning drive on their 45 and ate up 7:42.

On second-and-goal, Dalton pump-faked right and then ran up the middle, dived for the end zone and got the ball across for a 17-13 lead. Dalton said the Bengals called a screen but it was well-defended.

"I thought I was going to be able to throw it quick somewhere. But I wasn't able to, then I just found a lane and was able to get in.

"Not everything is going to go exactly as you plan. It's what you do when everything breaks down. It was a big play that we needed at that point."

Rivers had two turnovers in the final 3:54.

On the first Chargers' possession after Dalton's TD, defensive end Carlos Dunlap sacked Rivers, forced a fumble and recovered at the 13 to set up Mike Nugent's 24-yard field goal for a 20-13 lead.

Rivers was then intercepted in the end zone by Reggie Nelson on fourth-and-10 from the Bengals 17 with 49 seconds left.

"We were flat as hell the second half," Chargers fullback Le'Ron McClain said.

"Tonight for the most part, we didn't turn it over until the last two," Rivers said. "We're fighting like crazy to score. We're in a rut and all we can do is keep playing."

Keeping the Chargers' offense out of the end zone was "really big," Dunlap said. "That's huge because this team can put up a lot of points. They have a lot of scorers and great players on their offense. So for us to shut them out, that speaks volumes for our defense and that's just the foundation of what we want to do as a defense."

The Bengals overcame three turnovers, including two interceptions by Dalton. One of them was returned 31 yards for a touchdown by Demorrio Williams.

The Bengals took the game's opening kickoff and moved 91 yards, capped by Dalton's 19-yard pass to tight end Jermaine Gresham for a 7-0 lead.

Dalton threw an incompletion on fourth-and-9 from the Chargers 35, but Chargers cornerback Shareece Wright was called for holding and the drive continued at the San Diego 30.

The Chargers had a nice drive of their own and had a first-and-goal from the Bengals 7.

But Rivers fumbled when he was hit going back to pass. Tight end Antonio Gates recovered at the 16. The Chargers reached the 2-yard line but had to take Nick Novak's 20-yard field goal that pulled them to 7-3.

Two plays into the next Bengals drive, Williams intercepted Dalton and returned it 31 yards down the left sideline to give the Chargers a 10-7 lead. It was Williams' second interception returned for a touchdown this season.

The Bengals drove deep on the Chargers again and had a first-and-goal on the 5. A.J. Green was wide open in the end zone but Dalton overthrew him. BenJarvus Green-Ellis gained 4 yards to the 1, but an incomplete pass forced the Bengals to settle for Nugent's 19-yard field goal and a 10-10 tie.

San Diego made it to the Bengals 1 with a second before halftime and had to settle for Novak's 19-yard field goal for a 13-10 lead.

Game notes

San Diego is 21-23 since its last playoff appearance, a home loss to the New York Jets following the 2009 season. ... Bengals CB Dre Kirkpatrick sustained a concussion in the fourth quarter. ... Chargers RT Jeromey Clary had a knee injury in the first quarter and didn't return. ... Gates hasn't caught a TD pass in three straight games and remains one shy of tying Lance Alworth's team career record of 81. ... Williams also returned an interception for a touchdown in the Chargers' last win, 31-13 against Kansas City at home on Nov. 1. ... Robert Meachem, who was expected to help replace Vincent Jackson in the Chargers' offense, had zero passes thrown to him for the second straight week. It was his fifth game without a catch. ... The Chargers have been blacked out in Southern California for the second straight week and third time this season.