SAN DIEGO -- Yonder Alonso's propensity for hitting doubles helped his team to another win.
With two more doubles on Wednesday, Alonso has 23 this year and has hit two or more in a game seven times this season, which is a franchise record. Adrian Gonzalez and Tony Gwynn held the previous mark with six each.
"That's pretty unique," Alonso said. "It feels good when you're in the company of those guys. I knew what was going on and the guys on the team were making jokes about it. It's a cool moment for myself."
"It's so nice to have that type of padding in the game," Richard said. "You know you can make a couple of mistakes."
Richard fell short of his first career complete game and added an RBI double in the sixth.
"When you come to the ballpark as a starting pitcher, that's what you want to do," Richard said. "It's disappointing not making a few pitches at the end there to go through with it."
The Padres won for the fourth time in five games.
"It was a good performance today with contributions all around the lineup," Padres manager Bud Black said. "It's like we've talked about, that it's going to take all of our guys to get it done, and today was a good example of a lineup contributing top to bottom."
After Carlos Corporan singled to chase Richard in the ninth, Nick Vincent got one out but walked Jordan Schafer to put the tying run on deck. Huston Street entered and struck out Scott Moore to convert his 15th save.
"We've talked about Clayton's work ethic and what he does between starts, and he's equipped for a complete game," Black said. "I was pulling hard for him."
Downs' three-run home run in the sixth landed in the first deck of the Western Metal Supply Co. building in left field. He hit a solo shot off Richard in the ninth, also to left and has three home runs against Richard this season. Houston has lost 14 of 15 games on the road.
"He's very good," Downs said of Richard. "I think it's just he made two mistakes and I think they were both to me."
After Astros starter Wandy Rodriguez retired the first nine batters, the Padres broke through in the fourth.
The first six batters reached base, highlighted by Alonso's and Chris Denorfia's run-scoring hits. Rodriguez also walked two in the inning and threw a wild pitch as San Diego built a 5-0 lead.
"It's kind of tough to put your full finger on," Astros manager Brad Mills said. "That's kind of been his Achilles' heel, being able to stop those from getting started."
Rodriguez (7-8) allowed five runs and four hits over four innings, snapping a streak of 48 games in which the left-hander had lasted at least five innings.
"He didn't want to come out of the game, but we had to try to get a run on the board," Mills said.
Alonso's double in the seventh scored Denorfia and gave San Diego an 8-3 lead. Chase Headley scored on a Houston defensive breakdown in the fifth as Enerio Del Rosario threw wide of first base on an attempted pickoff. Headley ran to third and Downs skipped the ball past Chris Johnson as Headley scored.
Padres CF Cameron Maybin was scratched from the starting lineup with soreness in his right wrist. ... Astros C Jason Castro was to have his knee drained on Wednesday but is not expected to join the team this week. ... Lucas Harrell (7-6, 4.43 ERA) will take the mound for Houston in the final game of the series on Thursday. Edinson Volquez (5-7, 3.69) will start for San Diego.