HOUSTON -- For all the good work the Astros did on the pitching mound Sunday afternoon at Minute Maid Park -- they struck out 20 batters, setting a franchise record for a nine-inning game -- it wouldn’t have meant much had they not been able to polish off a sweep of the Angels. 

That wasn’t on Jeremy Peña’s mind when he came to the plate in the bottom of the ninth inning with the game tied, but the party he started by hitting a two-out, two-run walk-off homer off Ryan Tepera to send the Astros a 4-2 win enabled Houston to celebrate one of its most enjoyable wins of the season.

Peña, who is in the running for the American League Rookie of the Year Award after taking over the starting shortstop position from Carlos Correa, went a career-best 4-for-5 and logged the first multihomer game of his career. He also homered to right field in the fourth inning.

“To end it on a walk-off is unreal,” said Peña, who hit a walk-off homer against the Blue Jays on April 24. “It’s always fun walking it off. You get the win and we get to go home. It was great.”

The Astros (51-27) won their sixth consecutive game and have opened up a 13 1/2-game lead atop the AL West after sweeping the Angels. Houston has allowed six runs during this winning streak, all but one of which have come via solo homers.

“That was a good one to win,” Astros manager Dusty Baker said. “Everybody went home happy. Peña had a big day. He had four hits and a walk-off, and then [Jose] Altuve had a big day. And so we had some other guys have big days.”

Altuve, who went 3-for-5 in his 1,500th career game, started the ninth-inning rally with a two-out single. Peña, batting second, knew Tepera didn’t want to face slugger Yordan Alvarez, who was on deck, so he figured he’d get a pitch to hit -- and he did, crushing a first-pitch slider and sending it over Mike Trout’s head in center field for a Statcast-projected 429-foot two-run homer.

“Get a good pitch to hit and pass it to the next guy,” Peña said. 

• 'I got sneaky': Maldonado's heads-up play crucial to win

The Astros didn’t get any hits until the fourth, as the Angels sent Houston to its biggest in-game deficit since June 18 with a solo homer in the second by Luis Rengifo and an RBI single in the third by Shohei Ohtani off starter Framber Valdez to take a 2-0 lead.

Valdez delivered his 13th consecutive quality start and struck out a career-high 13 batters (against five walks), recording 12 consecutive outs via the strikeout from the final out of the first inning to the second out of the fifth, giving up some hits and walks between the whiffs. That smashed the previous franchise record of nine consecutive outs by strikeout, which had been done four times by three pitchers: Gerrit Cole twice, Randy Johnson and Don Wilson.

“I did feel a little bit uncomfortable because of all the walks I gave up today, but when I got focused, I said I was going to strike out more batters and attack the zone,” Valdez said. “I got excited for all the strikeouts, but definitely felt a little bit uncomfortable because of all the walks.”

Behind Valdez, the Astros became the first team in Major League history to strike out 48 batters in a three-game series without the benefit of extra innings, according to STATS. That included nine strikeouts of Trout, who went 0-for-11 in the series. 

“That lineup over there, they don’t chase much,” catcher Martín Maldonado said. “They always are going to be in the strike zone. Framber, he wasn’t attacking the strike zone like he has been in the past, and that’s why after the second inning, we kind of talked about it and said, ‘You have to throw strikes to these guys and let them get themselves out with that sinker and the curveball.’ And that's pretty much what we did.”