SAN DIEGO (AP) - The way the San Diego Chargers' offense is going, it's a wonder they had a fourth-quarter lead to blow against the Cincinnati Bengals.
Andy 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 staggering Chargers on Sunday.
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.
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 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.
The Chargers (4-8) lost their fourth straight game and for the seventh time in eight games, and remain mathematically, but hardly realistically, alive in the wild-card chase. Denver clinched the AFC West title on Sunday with a victory against Tampa Bay.
San Diego is 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.
``We were flat as hell in the second half,'' fullback Le'Ron McClain said.
Philip Rivers, once again scrambling behind a weak line, had two turnovers in the final 3:54 and was sacked four times.
San Diego's offensive line woes are also affecting the running game. Ryan Mathews had only nine carries for 26 yards.
``We can't run the ball right now,'' Turner said. ``We're struggling to run the ball against a front like that, so it certainly puts a burden on the offensive line, the protection and on Philip.
Mathews said he'd like more carries.
``I would. That's just me. I'm trying to do anything I'm asked for the team, whether that is two carries or 25 carries. I'm just a player. It is not up to me to be the coach.''
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.
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.
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.
Online: http://pro32.ap.org/poll and http://twitter.com/AP-NFL