49ers dim Steelers’ bid for AFC top seed – USA TODAY

The 49ers, having already clinched the NFC West, moved a step closer to securing a first-round bye with a 20-3 victory in a much-anticipated showdown that was delayed twice due to power outages.

San Francisco (11-3) broke open a tight game in the second half by battering and frustrating gimpy quarterback Ben Roethlisberger and stinging the gritty Steelers defense with a series of clutch plays.

• BOX SCORE: 49ers 20, Steelers 3

• VIDEO: Lights out in San Francisco

• MORE: Power outages hit Candlestick

Roethlisberger passed for 330 yards but was noticeably slowed by a high left ankle sprain suffered 11 days earlier. He threw three interceptions, lost a fumble, missed open receivers on several passes and could not extend plays with his feet in his typical style.

He was sacked three times, matching the season-low point total.

Yet while Pittsburgh (10-4) squandered a chance to gain sole possession of first place in the AFC North and aided a 49ers defense with numerous blunders, the 49ers gave away no such breaks.

They won with sound football, rather than explosive plays. Alex Smith passed for 187 yards, yet just as importantly wasn’t sacked and didn’t commit a turnover. He executed a beautiful 21-yard completion to tight end Vernon Davis on a throwback rollout pass in the third quarter that set up a 1-yard scoring toss to Davis on the next play that answered the Steelers’ only score — a 51-yard Shaun Suisham field goal — and pushed the 49ers’ lead to 13-3.

Early in the fourth quarter, after rookie Aldon Smith sacked Roethlisberger and forced a fumble recovered by Justin Smith, Frank Gore (18 rushes, 65 yards) cashed in with a 5-yard touchdown run for the final score.

David Akers opened the 49ers’ scoring with a pair of first-half field goals.

Kickoff was delayed for about 20 minutes after a transformer, located outside the stadium, failed. The power source was switched to a backup generator.

Yet early in the second quarter, a second outage caused a 16-minute delay.

At that point, suspended Steelers linebacker James Harrison, serving a one-game penalty for an illegal helmet-to-helmet hit, jokingly tweeted, “If I can’t play, nobody can play.”

The first play after power was restored? Offsides, 49ers.

It seemed fitting, the notion of a quick start.