Andrew Luck's return to the Bay Area was a smashing success, much to the chagrin of his college coach.
The ex-Stanford star ran for a touchdown while putting together an efficient effort under center, and the Indianapolis Colts clamped down on the defensive end on their way to an impressive 27-7 victory over the defending NFC champion San Francisco 49ers at Candlestick Park.
Luck completed 18-of-27 passes for 164 yards and did turn the ball over in outplaying young counterpart Colin Kaepernick, while getting a big assist from a Colts defense that held the struggling 49ers to 254 total yards and held Kaepernick firmly under wraps.
"That was a heavyweight fight right there," Colts head coach Chuck Pagano said. "Just a phenomenal, phenomenal effort."
Indianapolis (2-1) also churned out 179 rushing yards, with Ahmad Bradshaw gaining 95 and a touchdown on 19 carries and the newly acquired Trent Richardson scoring on his first touch as a Colt.
One week after committing four turnovers in a 29-3 loss at Seattle, Kaepernick managed just 150 yards on 13-of-27 passing while being intercepted once and losing a fumble.
"We have to be better," Kaepernick said. "I have to be better. I have to be able to make throws down the field."
Frank Gore finished with 82 rushing yards on 11 attempts for San Francisco (1-2), which fell under .500 for the first time in the three-year tenure of Jim Harbaugh, Luck's former mentor at Stanford.
Luck showed the skills and smarts that made him the No. 1 overall pick of last year's draft on the game's initial drive. He completed all five of his throws, including a 19-yard strike to Darrius Heyward-Bey that created a 1st-and-goal, in moving the Colts 80 yards in just seven plays to gain an early upper hand.
Richardson, obtained from the Cleveland Browns four days ago in exchange for a 2014 first-round pick, capped the sequence by powering over the goal line from a yard out 3:40 after the opening kickoff.
The Colts went three-and-out on their next two possessions, however, and the 49ers pulled even with a 9-play, 91-yard trek highlighted by three Gore runs that totaled 54 yards, the last a 21-yard scamper that put the ball on the Indianapolis 10.
Kendall Hunter was stuffed for a loss on the next play, but broke loose around the right side on his following carry for a 13-yard touchdown that tied the game at 7-7 with 4:13 left in the first quarter.
It was San Francisco's only sustained drive of the afternoon, though, as Indianapolis dictated the action the rest of the way.
A 12-yard punt return by T.Y. Hilton early in the second quarter gave the Colts the ball near midfield, and Luck engineered a pair of first downs to position Indianapolis for an Adam Vinatieri 43-yard field goal seven minutes prior to intermission, which turned out to be the deciding points.
The Colts carried that 10-7 edge into halftime, with Kaepernick hitting on only 2-of-8 passes for a meager 38 yards over the first two quarters.
Luck kept making crucial plays after the break. He scrambled for 15 yards on Indianapolis' opening series of the second half, then later hit Reggie Wayne for a 23-yard gain to set up Vinatieri's 41-yard field that extended the lead to six.
The Colts' defense, meanwhile, continued to clamp down on Kaepernick, who was further hindered by the absence of reliable tight end Vernon Davis due to a hamstring injury. With the 49ers' offense remaining stagnant, Luck led Indianapolis on a back-breaking 11-play, 80-yard sequence that consumed nearly half of the final quarter.
After four consecutive Bradshaw runs, most notably a 27-yard burst off the right side, got the Colts to the San Francisco 6, Luck scored untouched on a bootleg left to put San Francisco at a 20-7 deficit with just over four minutes left.
Three plays later, Kaepernick was sacked by Jerrell Freeman and fumbled at his own 8-yard line, with the Colts' Kavell Conner pouncing on the loose ball. Less than a minute after the turnover, Bradshaw crossed the goal line from a yard away to put the contest out of reach.
Richardson finished with 35 yards on 13 carries ... The Colts improved to 6-0 under head coach Chuck Pagano following a loss, while San Francisco fell for the first time in eight games under Harbaugh in that situation ... Niners All- Pro linebacker Patrick Willis left the game late in the third quarter with a groin injury and did not return ... Colts defensive lineman Ricky Jean- Francois, who spent his first four seasons with the 49ers, also departed with a groin issue in the second half ... Indianapolis played minus three starters in safety LaRon Landry (ankle), linebacker Pat Angerer (knee) and center Samson Satele (elbow) ... Harbaugh was the Colts' starting quarterback from 1994-97 before being replaced by Peyton Manning.