Dalton led the Bengals on a 14-play, 55-yard drive down the stretch and made the decisive scoring plunge after completing 25-of-39 passes for 211 yards and a touchdown.
BenJarvus Green-Ellis picked up 118 yards on 25 carries for the Bengals (7-5), who remained the AFC post-season picture with their fourth straight win.
The Chargers' Philip Rivers completed 26-of-48 passes for 280 yards but lost a fumble in the fourth quarter and tossed an interception in the end zone in the final minute.
Reeling San Diego (4-8) dropped its fourth straight.
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