SAN FRANCISCO — Colin Kaepernick stood in a cramped corner of the 49ers’ locker room smiling and chatting with Alex Smith late Saturday night when a stranger interrupted the two quarterbacks.
‘‘Wow, great game,’’ said former franchise quarterback John Brodie, shaking Kaepernick’s hand and patting him on the back. ‘‘Nice to meet you.’’
After a record-setting playoff debut that sent San Francisco to the NFC Championship game for the second straight season, Kaepernick needs no more introductions.
The second-year pro out of Nevada squashed all the questions and uncertainty about Jim Harbaugh’s in-season decision to supplant Smith as the starter in a 45-31 rout of Aaron Rodgers and the Green Bay Packers. Kaepernick is quickly becoming a household name, and his touchdown celebration — flexing his right arm and kissing his biceps — is trending all over social media.
Riding his strong legs and right arm, the 49ers (12-4-1) are back where they were a year ago and seemingly more dangerous and daring than when the eventual champion New York Giants eliminated them last January. San Francisco will play at Atlanta (14-3) Jan. 20 after the Falcons outlasted Seattle, 30-28, Sunday.
‘‘All the credit goes to him,’’ said rookie running back LaMichael James, another part of the dynamic read-option run game. ‘‘When he’s making that read, he knows when to give it. He knows when to pull it. He’s taking off. He’s faster than most people on the defense. He’s doing everything for us right now.’’
In the air and on the ground, Kaepernick confirmed Harbaugh’s much-debated move more than anybody could have imagined in 60 minutes of playoff football.
The tattoo-tattered quarterback from nearby Turlock, Calif., overcame an early interception returned for a touchdown and ran for scores of 20 and 56 yards, topping the rushing mark of 119 yards for quarterbacks set by Michael Vick in 2005 when Atlanta beat St. Louis. He also threw TD passes of 12 and 20 yards to go-to target Michael Crabtree, who finished with nine receptions and 119 yards in the NFC divisional matchup.
San Francisco racked up 579 total yards with 323 on the ground, scoring its third-most points in the franchise’s storied playoff history. And Kaepernick threw for 263 yards and ran for a playoff-record 181 yards.
‘‘It’s been amazing and I couldn’t ask for anything more,’’ Kaepernick said.
That’s something San Francisco sorely lacked last January.
Throw out the grind-it-out game that propelled the 49ers as far as a 20-17 overtime loss to the Giants a year ago. With a strong arm and quick-burst ability out of the pocket, Kaepernick has given the offense an added dimension — and maybe some moxie.
Crabtree’s one catch for 3 yards accounted for all of the production from San Francisco receivers against New York. While Kyle Williams bore most of the blame for his two fumbled punts, Smith and the offense struggled to move the ball and put the pressure on the defense most of the night.
Maybe no more.
All-Pro linebacker Patrick Willis credited Kaepernick and Co. for bailing out the defense, especially in the first half, when Kaepernick had 11 carries for 107 yards rushing to give the 49ers a 24-21 lead. Kaepernick simply ran away from Green Bay in the second half. , and the reigning MVP couldn’t keep up.
‘‘I joke with him all the time, I say, ‘You’ve got to be one of the biggest and strongest quarterbacks I’ve seen,’ ’’ Willis said.