SAN FRANCISCO — Drew Brees and the New Orleans Saints are right back on track.

Alex Smith and the San Francisco 49ers have completely skidded off the rails.

Brees passed for 336 yards and hit Marques Colston with three of his four touchdown throws in the Saints 31-10 win over the 49ers on Sunday. It was the third consecutive win for the Saints (3-4) and the fifth straight loss for the 49ers.

Reggie Bush had 113 total yards for the Saints, who jumped to a 24-point halftime lead with a steady offensive effort including catches by nine receivers and four scoring drives longer than 72 yards. Brees was on target, going 31-of-39 and avoiding any sacks for the fourth consecutive game.

With the highest-scoring performance of Colston's career and Bush's latest multifaceted game, the Saints were marching again. The 2006 NFC finalists have rebounded from their 0-4 start to move within one game of the NFC South lead.

Bush, who had his NFL breakout game with four TDs against the 49ers last year, had 64 yards on 10 carries and added seven catches for 49 yards. Terrance Copper also caught a TD pass, and David Patten had five catches for 109 yards.

While the Saints got it together, the 49ers (2-5) fell apart.

Alex Smith — Bush's high school teammate — and running back Frank Gore both struggled and the San Francisco defense couldn't keep the league's worst offense in it this time.

Smith, back in the 49ers' lineup after separating his right shoulder four weeks ago, went 22-of-43 for 190 yards with several noticeably bad throws. Gore twisted his ankle again in the second half, finishing with just 41 yards rushing.

After stopping their winless skid with a gritty victory at Seattle, the Saints have fattened up with wins over Atlanta and San Francisco. New Orleans will get a stiffer test next week from a tough Jacksonville squad, but everything seems better for Bush and Brees.

Meanwhile, the 49ers had an afternoon to forget in what's shaping up as another historically bad offensive season for the team that redefined the passing game in the 1980s.

San Francisco needed an 80-yard drive with the game already decided to surpass 200 yards of offense for just the third time all season.

Smith's return didn't help. After the Niners' opening drive ended with Smith wildly overthrowing Arnaz Battle, Patten flew past $80 million cornerback Nate Clements for a 43-yard catch on New Orleans' first play. Three plays later, Brees found Colston uncovered for the Saints' first score just 3:37 in.

Shawntae Spencer's 36-yard pass interference penalty against Colston on a flea-flicker set up Copper's 2-yard TD catch to cap a 91-yard drive midway through the second quarter, putting New Orleans up 17-0.

Colston, the second-year pro from Hofstra who had just eight catches in the last three games, caught a 3-yard TD pass 50 seconds before halftime. He made an exceptional play on his third scoring grab in the fourth quarter, leaping to get the ball and dragging his feet in the final inches of the end zone.

Tight end Vernon Davis caught a 7-yard TD pass for San Francisco with 4:16 left.