The Bengals then stuffed their fifth and last drive of the half when defensive tackle Pat Sims tripped up Gore on third-and-two to get the ball back with a minute left. Gore finished the half with 31 yards on nine carries and Smith went just 9-of-17 passing for 74 yards.

Bengals rookie quarterback Andy Dalton’s first two NFL interceptions came at the most inopportune moments Sunday in the Paul Brown Stadium opener when he fired two in the last 3:54 of a 13-8 loss to the 49ers before 43,363.

Cornerback Carlos Rogers jumped wide receiver Andre Caldwell’s sideline route with 3:54 left and the Bengals trailing, 10-6. That set up David Akers’ 53-yard field goal with 2:16 left to make it 13-6.

Then Dalton couldn’t get on the same page with tight end Jermaine Greshamrunning down the seam and with Gresham’s back turned safety Reggie Smith made a sliding catch at the 49ers 14 with 1:45 left. The Niners then took a safety with two seconds left.

Dalton’s bid for three straight 100 passer ratings to start his career ended at 40.8 on 17-of-32 for 157 yards.

The 49ers took the lead with less than five minutes remaining by going to their main man in a 72-play drive. Tight end Vernon Davis, finishing a 114-yard day, caught the killer, a play-action, throwback to the other side of the field from quarterback Alex Smith and Davis was wide open for a 20-yarder. Running back Kendall Hunter then walked in from seven yards out for the winning touchdown with middle linebacker Rey Maualuga in the locker room with cramps after he made what looked to be the winning play.

In a game the Bengals offense could do next to nothing, the Bengals defense did everything to try and win it.

Maualuga punched the ball out from 49ers running back Frank Gore and defensive tackle Jon Fanene recovered at the 49ers 16. But after running backCedric Benson banged out a 10-yarder on the next snap, the Bengals could only get a yard. On third-and-five Dalton looked at wide receiver Jerome Simpson for an alley-oop in the end zone when he was covered one-on-one, but he couldn’t get a release and Mike Nugent was called for a 23-yard field goal that gave the Bengals a 6-3 lead with 9:04 left.

The brilliant Bengals defensive effort finally got pierced, but not until 3:29 left in the third quarter and it was only Akers’ 23-yard field goal that tied the game as the Bengals staged a first-and-five rally from the Niners 6.

That was the same series that the Bengals allowed the Niners across midfield for the first time all day and Smith celebrated with his biggest play of the day on a 39-yard throw to Davis beating safety Reggie Nelson down the sideline to put the ball at the Bengals 6.

The Bengals then survived wide receiver Michael Crabtree’s touchdown catch and Maualuga’s unneccessary roughness call when he piled on after cornerback Nate Clements’ tackle. Crabtree’s TD got waved off when he stepped out of the end zone and came back in to catch it, and a botched snap moved the Niners back on a false start. Defensive tackle Geno Atkins then forced the field goal when he hauled down Smith at the 5 on third down.

But the Bengals offense couldn’t catch the momentum on the next series. They did manage to convert their first third down of the day with 12:40 left in the fourth quarter on Dalton’s three-yard throw to Gresham, but left guard Nate Livings’ holding call negated Benson’s 12-yard run and forced yet another unsuccessful third-and-long.

The Bengals third-down woes continued in the first half in a carryover from last week, but punter Kevin Huber pinned the 49ers inside their 20 on his first four kicks as the Bengals scratched out a 3-0 lead.

The 49ers’ best drive start of the game at that point came on the second-half kickoff when a touchback put them on their 20.

The crowd wasn’t happy that head coach Marvin Lewis decided to sit on the ball deep in his own territory with a minute left in the half, but he didn’t want to blow up a game his defense and special teams had dominated despite the offense going 0-for-6 on third down a week after struggling through a 1-for-11.

But as the players predicted during the week, the Bengals defense played much better than it did last week in Denver and held 49ers running back Frank Gore to four yards on his first three carries, sacked Smith twice in the game’s first 23 minutes, allowed the Niners wide receivers to catch just two balls on their first four series, and didn’t allow a third-down conversion until midway through the second quarter.

Defensive lineman Jonathan Fanene had the two sacks, the last when he looped outside from his tackle position to force Andy Lee’s fourth punt. The Niners were called for holding twice, and had four pre-snap penalties with three false starts. Fanene left early in the third quarter with a knee injury, but was to return.

The Bengals then stuffed their fifth and last drive of the half when defensive tackle Pat Sims tripped up Gore on third-and-two to get the ball back with a minute left. Gore finished the half with 31 yards on nine carries and Smith went just 9-of-17 passing for 74 yards.

Caldwell wasted no time replacing Simpson in the Bengals starting lineup when he caught three balls on the first drive, the last one a wide-open sliding 18-yarder at the 49ers 23 that Dalton threw under duress.

Dalton hit his first five passes for 61 yards, the last a play-action to tight endDonald Lee making his first Bengals appearance that got the Bengals to the San Francisco 6. Benson had a shot at scoring on the next play over the right side, but he stumbled at the 2.

From there the Niners right side stacked him up for a two-yard loss, and on third down Dalton rolled left and was nearly hauled down by former Bengals linebacker Ahmad Brooks racing past right tackle Andre Smith. Dalton got clipped just as threw into the end zone, where Simpson ended up breaking what could have been an interception, and the Bengals took Nugent’s 22-yard field goal with 8:44 left in the first quarter.

Early on Simpson, under a drug investigation, worked in the three-receiver sets and facing a third-and-10 on his second series, Dalton took a shot at him on the sidelines, but he was double-covered. Simpson did catch a ball later in the half and drew a mixed reaction.

The Bengals had trouble getting in sync after that first drive as the Niners run defense played as advertised. On their third series the Bengals tried Benson on second-and-10 and he just got three yards up the middle behind a line that replaced rookie right guard Clint Boling with Mike McGlynn. On third-and-seven rookie wide receiver A.J. Green false-started and Dalton had to throw a checkdown pass to Caldwell to get out of it with a punt.

Caldwell, whose career-high is seven catches, had five in the first quarter (and half) for 45 yards with his most impressive play an eight-yarder that was mainly yards-after-catch when he shrugged off Rogers and ran for the first down.

Trying to become the first rookie quarterback since Dan Marino to ring up 100 ratings in his first three starts, Dalton finished the half at 72.2 on 10-of-16 passing for 90 yards. But third down was brutal, and it wasn’t helped that two of the last three in the half were from 12 yards. Cincinnati's last full series began with Brooks going around Smith on the right edge for a sack.

The top-ranked Niners NFL run defense held Benson to 26 yards on nine carries in the half. Green, with two catches for 19 yards, was the only other Bengals receiver besides Caldwell with more than one catch.