SAN FRANCISCO » Drew Brees is getting plenty of extra chances, thanks to his opportunistic defense.

Last season, the New Orleans Saints won their games with a high-flying offense. So far this year they’re doing it on the other side of the ball. While Brees and Co. are finding their way early, the defense seems to be in midseason form.

Garrett Hartley kicked a 37-yard field goal that was partially blocked and fluttered through as time expired after Brees set it up with a 30-yard completion to Marques Colston, and the Saints spoiled the San Francisco 49ers’ home opener with a 25-22 victory last night.

"We’ve stayed with the mind-set we are the hunter, not the hunted," Brees said.

San Francisco’s Frank Gore ran for a 7-yard touchdown with 1:19 to play and Vernon Davis made a close-call catch at the goal line for the tying 2-point conversion. The play was initially called no good, but the 49ers (0-2) got the call after a replay review.

The defending Super Bowl champion Saints (2-0), who relied on their defense most of the game, got the ball back at the 30 with 1:14 left. Brees hit Colston with a pass that put the Saints on the 18 with 18 seconds left. The 49ers watched as Hartley’s kick just made it.

Ray McDonald got a hand on Hartley’s kick, but it just got there.

"I got half the ball, but I didn’t get enough," McDonald said.

Reggie Bush caught a 6-yard TD pass in his first game since giving back his 2005 Heisman Trophy won while with Southern California. The NCAA punished USC after concluding that Bush and his family took money and gifts from sports agents while Bush played for the Trojans.

Bush was helped off the field with a right leg injury with 6:58 left and then was taken to the locker room on a cart. No information was given on the severity of the injury.

"Everybody is giving us their A game," Bush said. "Everybody is giving us their best shot. We’re just finding ways to win. That’s all we can do is find ways to win. We can’t be down about a win like this. This is a great win against a physical team, a tough team. They came out and gave us their best shot. We still found a way to win."

Brees hit David Thomas for a 3-yard score that put New Orleans ahead late in the third quarter, and Tracy Porter’s interception at the 10-yard line preserved the lead until Gore’s late run.

"They played really well," Brees said. "You’ve got take your hat off to them; they played hard."

San Francisco outgained the Saints in yards 417-287 but beat itself with turnovers.

Roman Harper intercepted a pass by Alex Smith at the 26 in the first quarter. Malcolm Jenkins recovered Delanie Walker’s fumble at the 3 just before halftime as the Niners failed to capitalize on opportunities.

"We came in with the mind-set that we were going to win the turnover battle, and we did that decisively," Saints coach Sean Payton said.

On a festive evening at Candlestick Park in which the 49ers retired Hall of Famer Jerry Rice’s No. 80 jersey at halftime, the Niners looked little like the championship teams Rice starred on in the 1980s and ’90s.

Gore provided the highlight, running for 112 yards and catching a 12-yard touchdown pass from Smith. "It wasn’t like another team was out there beating us," Gore said. "We were beating ourselves."