GREEN BAY, Wis. — This wasn’t the new Alex Smith on display here Sunday, this was the old one.

This was the University of Utah Alex Smith, the quarterback in total control, relaxed, ready, brainy and dangerous.

This wasn’t the quarterback Mike Nolan broke, Mike Singletary discarded, and Jim Harbaugh had to revive with tender care last year.

No, on Sunday, Smith was beyond all that … and back to what he used to be: fully able to integrate mind and body into the flow of a very tricky contest.

This is an Alex Smith who can win big games. Huge games. Almost every game.

“He was just great all game,” Harbaugh said of Smith, who helped lift the 49ers to a rousing 30-22 win over Green Bay. “Used his legs, used his arm, used his mind, used his toughness.”

This wasn’t so much a new 49ers offense, either, though Randy Moss and Mario Manningham proved to be definite upgrades.

This was last season’s balanced 49ers offense, but run at maximum efficiency by a quarterback who isn’t second-guessing a single thing or instinct.

As part of that, Smith threw 26 passes without an interception — raising his streak to 185 dating to last season, which breaks Steve Young’s franchise record of 184.

So what does it mean when Harbaugh says Smith used his mind to beat Green Bay?

“That’s a good question,” Smith said. “I mean, I hope I used my mind … For me, it’s making good decisions. Being good with the football, being smart with the football.”

It was just coincidence that Smith had perhaps the sharpest game of his 49ers career against Green Bay and Aaron Rodgers. The 49ers took Smith with the No. 1 overall draft pick in 2005 and passed on Rodgers, who went on to win a Super Bowl and was last year’s NFL MVP.

But Sunday, Rodgers was the second-best QB on the field.

It was Smith, not Rodgers, who threw a snap touchdown pass to Moss in the first half and spoke about how happy he was for Moss to produce so quickly.

“Got a good look, what we were looking for, and yeah, he just blew open,” Smith said of Moss. “I think his eyes lit up bigger than mine.”

It was Smith, not Rodgers, who completed 20 of 26 attempts for 211 yards, two TDs and no interceptions. Smith had a 125.6 passer rating compared with Rodgers’ 93.3.

(Rodgers had more completions and more yards but also threw an interception to NaVorro Bowman in the fourth quarter.)

And, most important, it was Smith who won.

Interestingly, Rodgers apparently now has to wear Smith’s jersey in public after reportedly losing a bet with members of the band Boyz II Men, who sang the national anthem pregame.

“Someone told me about it,” Smith said when asked about the wager report. “So I’ll have to call him and get a picture of this.”

Of course, there were many other reasons the 49ers won this game.

They played tremendous “nickel” and “dime” defense for most of it, and they got production from just about every member of their offensive unit.

But the man who made it all seem natural was the quarterback — and he’s the one who has seemed so shaky in that role until recently.

“He had to be great in understanding what the Packers were doing, what we needed to do to counter that,” Harbaugh said.

Notably, the 49ers used backup Colin Kaepernick for one key play late in the first half, and Kaepernick’s dash for 17 yards set up David Akers’ record-tying 63-yard field goal.

Smith knows Kaepernick can come in from time to time throughout this season, and he understands.

“Check your ego, you know?” Smith said.

That’s another sign this isn’t a new Alex Smith, it’s the old, unthreatened one. He’s thinking through the game plan right along with Harbaugh and offensive coordinator Greg Roman, and he sees the logic in using Kaepernick, too.

“That was fun to watch, wasn’t it?” Harbaugh bellowed at the end of his news conference.

He was talking about the performance of his entire team, but he had to be talking about Smith, too.

Last year, the team and QB were a reclamation project. Now, already, after just one week of the 2012 season, the 49ers and Alex Smith are comfortably in the NFL elite.

You’d have to be dumb to ignore that, and nobody here is anything close to dumb.