The Chargers took advantage of Dalton's three turnovers in the second half on Sunday, pulling away to a 27-10 victory that extended San Diego's late-season surge and pushed the Bengals' postseason misery to record levels.
With Rivers making accurate throws in the chilling rain, the Chargers (10-7) won their fifth in a row, beating the last team that had knocked them off. They'll play next Sunday in Denver, which has the AFC's top seed.
The Chargers lost at home to the Broncos 28-20 on Nov. 10, then went to Denver and got a rejuvenating 27-20 victory on Dec. 12 that gave them momentum.
"We will be confident," said Rivers, who was 12-for-16 for 128 yards with a touchdown and no interceptions on a rainy, 40-degree afternoon. "We've got to be careful we're not overconfident, which we won't be. Cincinnati came to our place and won five weeks ago."
The Bengals (11-6) won in San Diego 17-10 on Dec. 1, starting their final push toward the AFC North title. They took advantage of three turnovers in that one.
They turned it over four times Sunday, with Dalton's fumble and two interceptions in the second half leading to one of the most stunning losses in franchise history. The Bengals had been 8-0 at home and brought the NFL's No. 3 defense their highest-ever playoff ranking into the game.
With everything in their favor, they unraveled in the second half, getting outscored 20-0.
"Whatever you do during the regular season doesn't matter once you get to the playoffs," said Dalton, who is 0-3 in the playoffs. "It's disappointing. All the good stuff we did this year, then to come out and not win this game kind of hurts."
A lot of it falls on Dalton, who has a trilogy of bad playoff games. He fumbled and threw two interceptions in the second half. Dalton finished 29-for-51 for 334 yards with a below-average passer rating of 67.
The Chargers pressured him in the second half and took advantage of his mistakes. And they didn't turn the ball over in a conservative offense that sometimes grated on Rivers but ultimately worked.
"The way our defense was playing, as long as we didn't have a disaster and we made plays when they were there, we were going to win this game," Rivers said.
Combined with the Saints' victory over the Eagles on Saturday night, the two No. 6 playoff seeds won for the first time since 2010, when the Packers won the Super Bowl.
"We're loose, we're confident, we're peaking at the right time," safety Eric Weddle said. "We are a team to be dealt with. We're a confident bunch, especially in the second half, in the fourth quarter. We feel we're ready for those situations. The pressure is not going to get to us."