SANTA CLARA, Calif. -- The Cincinnati Bengals demonstrated Sunday that the best remedy for an injured quarterback is an opportunistic defense.

Running back Jeremy Hill scored a pair of one-yard touchdowns in a second-quarter flurry fueled by San Francisco 49ers mistakes, and the Bengals clinched a playoff spot and at least a share of the AFC North title with a 24-14 victory.

Quarterback AJ McCarron passed for 192 yards and 20-yard score to backup tight end Tyler Kroft in his first start in place of injured Andy Dalton, who likely will miss the rest of the regular season with a fractured thumb.

McCarron's 15-for-21 starting debut wasn't spectacular, but it didn't have to be on a day when the Bengals intercepted three passes, recovered a fumble and sacked 49ers quarterback Blaine Gabbert four times.

"They say a quarterback's best friend is a good run game and a good defense," Bengals nose tackle Domata Peko said. "We were just trying to do our part. What we have to do is handle our side of the ball, and I think we did that for the most part today."

The win kept the Bengals (11-3) one game behind New England (12-2) in the race for the best record in the AFC and was their first on the road against the 49ers since 1974, their first meeting in San Francisco.

Gabbert completed 30 of 50 passes for 295 yards and a score for the 49ers, who fell to 4-10. Only two teams -- Tennessee (3-11) and Cleveland (3-11) -- have fewer wins.

"We were throwing them and we weren't catching them," 49ers coach Jim Tomsula cited as the chief reason his team's downfall. "Until we understand that we cannot make those fundamental mistakes ... We have to make those plays."

Cornerback Adam Jones, linebacker Vontaze Burfict and safety Shawn Williams recorded interceptions for the Bengals, but defensive end Carlos Dunlap was the defensive star with a fumble recovery that set up Cincinnati's first score and a blocked field goal that denied the 49ers three critical points late in the game.

"That's what they did: They made it easy," 49ers defensive end Quinton Dial said of the role the Cincinnati defense had in making McCarron comfortable. "He's a good game manager."

The teams battled through a scoreless quarter and a half before Dunlap ignited a 21-point Bengals' second-quarter explosion when he dropped back into pass coverage and wrestled the ball away from 49ers wideout Anquan Boldin after a 12-yard completion.

Dunlap returned the fumble recovery 21 yards, setting up the Bengals at the San Francisco 11 with 8:01 remaining in the second quarter.

Hill's first touchdown came five plays later, a one-yard plunge that was initially ruled to be stopped short of the goal line before it was challenged by the Bengals and ruled a score on review with 5:16 left in the half.

"They had turnovers, we didn't, and that's the key to the game," McCarron said. "I felt good about it."

It didn't take long for the Bengals to take complete control from there.

An 18-yard punt by 49ers rookie Bradley Pinion gave Cincinnati possession at the San Francisco 36 with 3:22 remaining in the half.

Again it took the Bengals just five plays to score, with a 19-yard connection from McCarron to wideout Mohamed Sanu setting up Hill's second one-yard dive for a 14-0 lead with still 2:05 left in the half.

Things then went from bad to worse for the 49ers when a Gabbert pass bounced off the hands of tight end Vance McDonald and into the arms of Burfict for Cincinnati's second interception of the game.

On the play following Burfict's 15-yard return, McCarron found Kroft, who was subbing for star tight end Tyler Eifert (concussion) for a 20-yard touchdown and a 21-0 lead with 53 seconds left in the half.

"Routine catch," the 49ers' McDonald said of his critical mistake. "It's frustrating. That one's on me."

McCarron finished 15-for-21 without throwing an interception.

The Bengals' lead became 24-0 when Mike Nugent capped Cincinnati's best drive of the day, a 13-play, 70-yarder, with a 22-yard field goal after the visitors had taken the second-half kickoff.

"I'm proud of our guys for coming out here and taking care of business today," Bengals coach Marvin Lewis assured. "It wasn't perfect. But ... we got the win, and we'll move forward now."

The 49ers caught a break of their own to produce their first points of the day, taking over at the Cincinnati 46 later in the third quarter when nose tackle Ian Williams recovered a Hill fumble.

Gabbert connected with Boldin for 29 yards on the next play, setting up a one-yard touchdown dive by fullback Bruce Miller that shortened the deficit to 24-7 with 3:14 remaining in the period.

"Anytime you don't come out and perform the way you're capable of performing, it's frustrating," assured Boldin, whose eight receptions led all pass-catchers. "Too often we get off to slow starts and then try to get it cranking in the second half. That shouldn't be the case."

The 49ers' next serious scoring opportunity was thwarted when Dunlap blocked Phil Dawson's 41-yard field goal attempt with 8:06 left in the game.

Gabbert's 15-yard touchdown pass to Boldin with 2:17 to play capped the scoring.

NOTES: Bengals WR A.J. Green, a late addition to the injury report Saturday with a back issue, started the game but had just one catch for 37 yards. ... The Bengals defense denied the 49ers a first down on each of their first 12 third-down attempts until late in the game. ... The 24 points allowed were the most by the 49ers in a home game this season. ... The blocked field goal in the fourth quarter snapped 49ers K Phil Dawson's streak of having made 19 in a row since a miss in the opener. ... The 49ers lost RB Shaun Draughn to a knee injury in the second quarter. Draughn nonetheless was the game's leading rusher with 38 yards on nine carries. ... The 49ers hosted a reunion of their 1981 and '88 championship teams, both of which beat the Bengals in the Super Bowl, during a halftime ceremony. The celebration, originally scheduled for prime time until NBC flexed out of the game, featured Joe Montana and Jerry Rice.