SAN FRANCISCO (AP) -- Trent Richardson practiced all of twice with his new team before helping lead Indianapolis to what Colts coach Chuck Pagano already considers a signature win.
Richardson and Ahmad Bradshaw gave Andrew Luck quite the 1-2 punch in the running game, each rushing for a 1-yard touchdown for the Colts in an emphatic 27-7 victory on the San Francisco 49ers' home field Sunday.
"I love playing with Luck out there," Richardson said. "He is a good person, a genius, and a rocket scientist out there. Playing beside him you must know your stuff."
With only a few days in this system, Richardson crammed as much as he could to prepare for the 49ers (1-2) after being traded by the Browns on Wednesday.
He carried 13 times for 35 yards, while Bradshaw gained 95 yards on 19 rushes. Everybody involved credited a patchwork offensive line for its steady play despite all the changes.
Richardson's first touch was good for a touchdown in his Colts debut.
"Trent Richardson being here for a Thursday and a Friday practice and he's playing in the game and scores a touchdown, are you kidding me?" Luck said.
Luck got the best of college coach Jim Harbaugh in his return to the Bay Area, where he shined at Stanford before becoming the No. 1 pick in the 2012 draft.
"To me it's a good win because we beat a good team," Luck said. "The connection, the college coaches, that didn't really factor into it and how I felt about the game. I respect those guys so much."
Here are five things learned from the Colts' lopsided win against the NFC champions:
1. STRUGGLES FOR 49ERS' D: Not only did the 49ers give up big plays on defense and make costly penalties, they lost All-Pro linebacker Patrick Willis to a groin injury and learned linebacker Aldon Smith is headed to rehab and going to be away indefinitely following his arrest Friday morning on suspicion of DUI and marijuana possession.
San Francisco gave up 336 total yards. And that game at St. Louis on Thursday night will be here in a hurry.
"Stunned. We didn't play 49ers defense," safety Donte Whitner said. "We'll go back to the drawing board and we'll get it all corrected, come out and play with passion, be physical and disciplined and we'll go in and get a win Thursday."
2. STINGY DEFENSE: The Colts were the ones with the stingy front seven swarming Colin Kaepernick at every chance and the secondary that didn't let the 49ers find anything easy down field.
San Francisco never got into a groove.
"We had to make a statement," said defensive tackle Ricky Jean Francois, who went to the Super Bowl with San Francisco last season.
As 10½-point underdogs on the road against a top team, the Colts were out to prove a point -- and they did just that.
"Nobody in the world gave us a chance," defensive end Cory Redding said.
3. STAGNANT OFFENSE: San Francisco managed 13 catches all day. Anquan Boldin had 13 himself in a sensational 49ers debut two weeks ago.
It has been two straight lackluster games for the offense following that impressive season-opening win against Green Bay. Kaepernick threw for a career-high 412 yards that day and Boldin seemed unstoppable.
With tight end Vernon Davis sidelined by a hamstring injury, Boldin had five of the team's 13 total receptions. The 49ers managed only 254 yards of offense and have been held to just 10 total points over the past two games.
Kaepernick was 13 for 27 for 150 yards with an interception and three sacks.
"I have to be able to throw to open receivers and give them a chance to make plays," Kaepernick said.
4. GORE'S GAINS: Two years ago, Frank Gore started the season slowly in the first three weeks. Then, he busted off five straight 100-yard performances.
The 49ers' all-time rushing leader came into Sunday with 60 total yards, and topped that on their second series with three big runs including one for a season-best 22-yard gain.
He finished with 82 yards on 11 carries and also a pair of catches. He now has 2,687 career yards receiving, moving into second place in franchise history for a running back behind Roger Craig (4,442).
Still, there was little to celebrate.
"We just haven't made plays," Gore said. "We've got to look at ourselves and see what's going on, and see what we're not doing right."
5. MORE PENALTIES: Jim Harbaugh vowed to clean up San Francisco's penalty problems, yet this wasn't the day for strides when it came to flags flying. They have 29 through three games.
Two snaps into the game, two penalties by the 49ers' defense.
Cornerback Tarell Brown had three of San Francisco's six penalties for 48 yards -- two pass interferences and a holding.
"It was a rough day," he said. "I think nine times out of 10 I would have got those calls or they would have gone my way. But I guess the referee saw something different. It happens. I'm not going to change my style of play and I'm going to play aggressive."
AP NFL website: www.pro32.ap.org