NEW ORLEANS – Ahmad Brooks played wide receiver in high school. And he returned kicks in college.

So when the 259-pound outside linebacker saw a Drew Brees pass sailing his way in the second quarter Sunday, his instincts took over. Brooks snatched the ball out of the air and then outraced the Saints, including Brees, for the end zone, one of two scores for the 49ers' defense.

The touchdown tied the score 14-14 entering halftime, and it negated an interception two plays earlier by Colin Kaepernick, returning the momentum to the 49ers.

"It was like he was shot out of a cannon," coach Jim Harbaugh said of Brooks' 50-yard return.

Said Brooks: "I actually kind of felt kind of slow."

Brooks was part of the group that tormented Brees in the second half.

In the third quarter, Donte Whitner scored on a 42-yard interception return after fellow safety Dashon Goldson upended wide receiver Marques Colston, who tipped the ball to Whitner.

Brooks, Justin Smith and Aldon Smith finished with 1 1/2 sacks each. Aldon Smith leads the league with 16 1/2 sacks. Brooks also had five tackles, two quarterback hits and one tackle behind the line of scrimmage.

It was one of Brooks' best games as a 49er, and it came in front of his mother, grandmother and a crowd of cousins, with whom he spent holidays and summers as a boy.

Brooks' father, former NFL defensive lineman Perry Brooks, died in 2010 and is buried an hour and a half from New Orleans, Brooks said.

"I've got a lot of memories here. This is my second home," he said, emotion showing on his face. "It feels good to do it here. It feels great."

Return woes – The 49ers fear backup kick returner Kyle Williams tore knee ligaments and will be lost for the year.

Williams, who suffered the injury at the end of the third quarter, had an increased role on returns Sunday because Ted Ginn was dealing with a wrist issue, Harbaugh said.

It's not known whether Ginn's wrist was to blame for a second-quarter muff of a punt return in which he appeared to start moving before he secured the ball.

The Saints recovered at the San Francisco 11-yard line, and two plays later, Brees found Colston in the back of the end zone to put New Orleans ahead 14-7.

It was the sure-handed Ginn's first fumble since he joined the 49ers in 2010. The next time the Saints punted, Williams was back to return it.

The Saints did not punt after Williams left. If they had, defensive back Perrish Cox likely would have handled the return for the 49ers.

Cox and second-round pick LaMichael James, who has been inactive every week this season, can handle punts if those ahead of them on the depth chart are injured.

Entering Sunday's game, Williams was fifth on the 49ers in receiving yards with 212. In addition to his backup role as punt and kick returner, he is the emergency backup quarterback.

A first for Jacobs – Brandon Jacobs finally had his first carry with the 49ers.

The big running back was active Sunday for the second time this season. In the fourth quarter, he carried the ball for one yard on second and 18, his first and only carry with his new team.

He carried for two yards in the third quarter, but the play was rubbed out by a holding penalty on backup offensive lineman Leonard Davis.

Jacobs could see even more action this week.

The 49ers' top backup running back, Kendall Hunter, left later in the third quarter because of an ankle injury and did not return. He had to be helped to the sideline and was carted into the locker room.

If Hunter can't play Sunday at St. Louis, Jacobs could take his place. James also could fill in.

Defensive play – Randy Moss was held without a catch for the second time this season. But the veteran wide receiver made one of the defensive plays of the game.

Early in the fourth quarter, the 49ers had driven to the New Orleans 5-yard line and were attempting to pull ahead by two scores. Kaepernick's pass to Moss in the corner of the end zone, however, was poor, and cornerback Malcolm Jenkins appeared to have an easy, momentum-swinging interception.

But Moss switched roles with Jenkins, playing defensive back and knocking the ball away. The Saints and the Superdome crowd roared for a penalty on Moss, but none was called. Two plays later, David Akers kicked a 27-yard field goal, the final score of the game.

Said running back Frank Gore of Moss' play: "It was either him or no one. He made sure it was no one."

Injuries – Tight end Delanie Walker (hip) left in the second half and did not return. Right tackle Anthony Davis was examined by the team's medical staff at the end of the game, and his injury was unknown. Aldon Smith (shoulder) briefly left the game.

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