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SAN FRANCISCO -- Alex Smith and the San Francisco 49ers picked up right where they left off last season.

So much for an NFC title game hangover.

Smith tossed a 4-yard touchdown pass to Brett Swain on the opening possession, backup Colin Kaepernick ran 78 yards for a score on the next and the 49ers breezed past the Minnesota Vikings 17-6 Friday night in the preseason opener for both teams.

"I thought they were on top of their business," 49ers coach Jim Harbaugh said.

Sure looked like it all the way around.

Brandon Jacobs, Kendall Hunter and Rock Cartwright combined for 69 yards rushing on the first drive to lead a reloaded running back group for San Francisco on a night three-time Pro Bowler Frank Gore rested. Smith finished 3 for 3 passing for 16 yards.

San Francisco had 260 yards rushing to Minnesota's 82 yards.

"We ran the ball really well that opening drive and all game," Smith said. "Anytime you can do that it just makes our jobs a lot easier."

The only real shortcoming for the Vikings' regulars came on the scoreboard.

Christian Ponder completed 4 of 9 passes for 80 yards, and Toby Gerhart ran for 31 yards for Minnesota in place of rehabbing starter Adrian Peterson. The Vikings offense showed promise, moving the ball with ease until settling for field goals of 39 and 26 yards by new kicker Blair Walsh in Candlestick Park's whipping winds.

"We would have liked to have come out with touchdowns rather than two field goals," Ponder said. "But it was a pretty good start. There were a lot of positives. We moved the ball well against a really good defense."

Randy Moss made his 49ers debut after sitting out last season, though it was hard to notice. The 35-year-old wide receiver, who signed a one-year deal with San Francisco, played sparingly and was never targeted.

In the first game at Candlestick since the overtime loss in the NFC championship to the New York Giants on Jan. 22, the new-look 49ers started strong.

Jacobs, who signed a one-year deal with San Francisco after winning his second Super Bowl with New York, showed his strength in short-yardage situations -- a missing element for the 49ers last season -- by running for 3 yards on fourth-and-1 from San Francisco's 47 to extend the opening drive. He added a 23-yard sprint and finished with 31 yards on the ground. All four of his rushes led to a San Francisco first down.

The big, burly running back's transition seemed seamless.

"It's always the first question," Harbaugh said. "Just human nature, you're trying to find out what's in another man's heart. Is he about us? Is he about himself? It has been a great group, from first-year guys to 10-plus year guys. I think it's been a good fit."

San Francisco also received rushes of 19 yards by Cartwright and 14 by Hunter to set up Smith's short fade to Swain that finished off the first-team's only possession. The 12-play, 84-yard drive lasted 7:21 and resembled the kind of grind-it-out fight that helped the 49ers to a 13-3 regular season last year and the franchise's first playoff appearance in a decade.

For a team that relied so much on defense a year ago, the offensive blitz -- even for the preseason -- could go a long way to lift San Francisco's spirits.

Kaepernick, the former Nevada quarterback drafted 36th overall last year, kept a read-option on his second play from scrimmage for a 78-yard touchdown, sprinting down the right side almost uncontested. He stiff-armed cornerback Chris Cook the final 20 yards, tossed the ball when he reached the end zone and flung his arms wildly in celebration after giving San Francisco a 14-6 lead. He threw for 40 yards on 5-for-9 passing and had 90 yards rushing.

"I felt very much at home when I saw that hole open up," Kaepernick said. "I had a flashback there."

Not a bad opening act.

Maybe the only major blemish for the 49ers came when linebacker Aldon Smith, the runner-up for AP Defensive Rookie of the Year, left in the first quarter with what the team called a bruised hip. Harbaugh said he was still waiting to hear from team doctor, but "preliminary (results) looks like we'll be all right, looks like we'll dodge a bullet there." Smith walked out of the locker room without talking to reporters.

The other hiccup came when Carlos Rogers bit on an outside fake by Stephen Burton and thought he had safety help over the middle on Minnesota's first possession. Burton sliced back inside and caught a 52-yard pass from Ponder to put Minnesota at San Francisco's 24-yard line.

While the Vikings starters moved the ball often, they never found the end zone.

Gerhart, the 2009 Heisman Trophy runner-up under Harbaugh at Stanford, carried the bulk of the offense, including a 16-yard scamper to San Francisco's 12-yard line. But drives for Minnesota's regulars ended in field goals by Walsh, who is replacing longtime veteran Ryan Longwell.

"If we can turn this 3s into 7s, that's really going to be a big thing for us," Vikings coach Leslie Frazier said. "That's something we talked about all offseason. We need to get those 7s."

Game notes

Vikings DT Letroy Guion left in the first quarter because of a strained knee and will be out 1-2 weeks, said Frazier, who didn't know which knee was injured. ... Former 49ers coach Mike Singletary handed out hugs and handshakes during pregame warm-ups. The game marked the first time Singletary -- now the Vikings linebackers coach and special assistant to Frazier -- was back at Candlestick since San Francisco fired the Hall of Fame linebacker after a 5-10 start in 2010. ... Vikings WR Percy Harvin, CB Antoine Winfield and DL Kevin Williams and Jared Allen were not in uniform. ... DL Justin Smith and Will Tukuafu and WR Mario Manningham were among the San Francisco notables given the game off, which is typical for veterans in the preseason opener.