NEW ORLEANS -- San Francisco 49ers quarterback Jimmy Garoppolo ventured into the Mercedes-Benz Superdome for the first time Sunday to play the high-powered New Orleans Saints.

For as much as Garoppolo enjoyed the chance to play in a playoff-type atmosphere in one of the most difficult venues in the NFL, Garoppolo was equally intrigued to see how he would stack up against Saints quarterback Drew Brees in a game that closely resembled a 60-minute fast break.

"Drew, obviously, is one of the best ever," Garoppolo said. "I love watching him play, I love studying him on film. The guy is unbelievable. To be in a game like this, we didn't know how the game was going to go."

How it went was Brees and Garoppolo treating the Superdome like the MGM Grand Garden Arena, walking to the middle of the ring, touching gloves and tossing haymakers until the clock was all zeroes. When time did expire, it was Garoppolo, not the future Hall of Famer Brees, standing tall with a 48-46 victory that moved the Niners to 11-2 and gave them a leg up on New Orleans in a potential battle for the NFC's top seed.

Garoppolo posted one of his most prolific games, finishing 26-of-35 for 349 yards and four touchdowns with an interception for a passer rating of 131.7. It was his third 300-yard, four-touchdown-pass game this season. His 75-yard pass to receiver Emmanuel Sanders was also the longest touchdown pass of his career.

"I feel like we've been here before," Sanders said. "Jimmy is a baller. You can look at him and see what kind of player he is. He works hard. When you've got somebody like Jimmy with the personality that he has, in the clutch moments he's not going to fold."

As the 49ers head down the stretch, having Garoppolo firing on all cylinders -- particularly in big moments -- is a critical development for a team harboring legitimate Super Bowl dreams.

For much of the season, the Niners' doubters have pointed to Garoppolo as the team's biggest question mark. It wasn't that Garoppolo was incapable of delivering in big moments so much as the cynics having not seen it, especially against a tough opponent on the road.

Well, they don't get much bigger than the Saints, who entered Sunday's game 10-2 and in control of the NFC's top seed. Making matters more difficult for Garoppolo & Co. was a raucous crowd that left Garoppolo nearly without a voice from the screaming required to deliver plays in the huddle.

"I think it gives him a ton of confidence," cornerback Richard Sherman said. "I think he hasn't cared about what the naysayers and the outside world has thought this entire time, but I think it's a wake up call for them as well of the quarterback he can be, of the quarterback he is during clutch moments ... the crucial moments of the game. I think there's been a lot of question marks, and I think he answered a lot of questions tonight."

Against the Saints, Garoppolo attempted a career-high 14 play-action passes, going 11-of-14 for 191 yards and two touchdowns. He also excelled on the move, throwing three of his touchdowns outside the pocket, marking the first time in his career he had multiple scoring strikes outside the pocket. He was 6-of-7 for 100 yards on those passes, setting a career high for yards and tying for a career high in completions, according to ESPN Stats & Information research.

Perhaps most important, Garoppolo was at his best when it mattered most. He engineered the game-winning drive with a big assist from tight end George Kittle on a key fourth-down play just a week after a fourth-down incompletion intended for Kittle left the Niners' upset bid short against the Baltimore Ravens.

Moments after the Saints had stormed back from a 9-point deficit to take the lead with 53 seconds left, Garoppolo calmly entered the huddle and told his teammates it was time to get to work.

"This is a big game and he played big time," Sherman said. "He played like the best quarterback in football today. He beat a legend. Drew Brees gave them a chance at the end, got them a touchdown, but you've got to give Jimmy Garoppolo credit. That was a shootout, and he got the last shot."

It's a shot Garoppolo made and one that sent a resounding message that the Niners, who have leaned so heavily on their defense to carry the load all season, have a quarterback who is able to get it done in the toughest conditions when the lights are the brightest and the stage is the biggest.

"I think he's at the top of the league in what he's capable of doing," right tackle Mike McGlinchey said. "We've known that for a long time, and I don't know why everybody on the outside has doubted that. But Jimmy is the man. Jimmy is the guy we want at the helm, and he showed why today and the sky is the limit for him."

If the Garoppolo who delivered the biggest win of the season Sunday is the same one who shows up the rest of the season, the same could be said of the 49ers and their postseason dreams.