It came down to trust.

The final minutes had unfolded at a dizzying pace. Fourteen seconds remained. San Francisco trailed New Orleans 32-29 and faced third-and-4 from the Saints' 14-yard line.

New Orleans was in zone coverage with two safeties back. Vernon Davis was in the slot left, Alex Smith in the shotgun. The ball was snapped, and Smith started his delivery before Davis, running straight downfield, even cut inside. Smith was throwing to a spot he trusted Davis would reach before Roman Harper.

Smith trusted his arm. He trusted his read. He trusted his offensive line. He trusted Davis.

And perhaps more telling than anything, 49ers coach Jim Harbaugh trusted Smith enough with the season on the line, in the red zone, where a mistake could end it all, to go for the win rather than play it safe for the tie and try again in overtime. Smith delivered the ball at just the right time, a split-second before Harper could get to Davis, who made the catch at the goal line to win the game.

Think about it. Harbaugh put the ball in Smith's hands and said, "Go win this," even though all season Harbaugh had asked Smith to be the caretaker of the 49ers' offense, to not make mistakes, to not turn it over, to let the defense and the run game and the spectacular special teams carry the load.

It was a fantastic catch by Davis, there is no doubt, but it was a better throw by Smith.

"He looked like Joe Montana," Ron Jaworski said on Tuesday while watching the coaches' tape of the game at his office at NFL Films. "Eventually, you have to make plays. I think in this game he actually made plays that won the game for them. Alex Smith won the game, not Alex Smith by not making mistakes. His performance won the game for them."

Since San Francisco selected him No. 1 overall in the 2005 draft, Smith has endured a parade of head coaches and offensive coordinators. Not since his second season, when Norv Turner was the Niners' offensive coordinator, has Smith had a teacher like Harbaugh. A former NFL quarterback, Harbaugh understands the nuances of the position. He sees what Smith sees. And clearly the two have developed a mutual trust in each other.

That was on display late in the game Saturday.

Smith has changed people's opinion of him in the Bay area. AP Photo/Paul Spinelli

On Tuesday, I watched the game film first with Greg Cosell, the long-time executive producer of ESPN's "NFL Matchup," then with Jaworski. Both said Smith's play in the final four minutes of the game was a gigantic step in his maturation process, and that he made three throws that were as technically sound as any top quarterback in the NFL could make. They were throws, both men noted, that Smith had not been asked to make all season.

The first play came with 3:14 left. New Orleans had just taken its first lead of the game (24-23) on a 44-yard Darren Sproles reception. On second-and-10 from the San Francisco 33-yard line, Davis was split left, the lone receiver on that side, with two receivers on the right. The Saints were in cover-zero, an aggressive formation Cosell pointed out they played on about 10 snaps, with Malcolm Jenkins on Davis in man coverage. It was a matchup San Francisco undoubtedly liked, given the tight end's speed against the slower safety.

With a blitz coming, Smith dropped back and started his throwing motion before Davis had run 10 yards. He quickly lobbed the ball 37 yards and it fell over Davis' shoulder and into his hands for a huge gain. Three plays later, on a called quarterback run, Smith rushed 28 yards around left end and got huge blocks by wide receiver Kyle Williams on the edge and left tackle Joe Staley downfield to score a touchdown.

After the Saints answered to regain the lead, 32-29, with less than two minutes to play, New Orleans opened the 49ers' ensuing drive in its prevent defense. But Smith completed two check downs to Frank Gore, forcing the Saints back to their man-to-man.