PHOENIX -- The Arizona Diamondbacks were looking to spoil Houston's postseason aspirations.
In Friday night's series opener at least, they failed miserably.
Dallas Keuchel became the AL's first 20-game winner and the Astros routed the Diamondbacks 21-5.
It was the most runs Arizona has allowed in franchise history.
"We just couldn't slow them down," Diamondbacks manager Chip Hale said. "Tonight we will take a shower and get rid of this game and have a better one tomorrow."
Houston manager A.J. Hinch had worried about not getting to use the designated hitter for this final series because he's in an NL park. At least on this night, he needn't it.
"I don't want to play the National League style at the end of the season because I want the DH," he said, "but this game is crazy. Sometimes strange things happen. This is a hitter-friendly park with the roof open, and we came out swinging and did a lot of damage."
The Astros have won five of six and held their one-game edge over the Los Angeles Angels for the second AL wild-card spot. Minnesota fell two behind.
Houston trails West leader Texas by two games with two to play.
Keuchel (20-8) gave up two runs on six hits in six innings, becoming the Astros' first 20-game winner since Roy Oswalt went 20-12 in 2005.
Carlos Correa hit a solo homer, bases-loaded triple and singled, and scored four times. George Springer, Colby Rasmus and Luis Valbuena homered as Houston surpassed its previous high of 19 runs set twice, most recently against Pittsburgh in 1999.
Springer and Rasmus also scored four times each as the Astros got a season-high 19 hits.
Keuchel is the 10th Astros pitcher, and second Houston left-hander, to win 20. Mike Hampton was 22-4 in 1999.
Keuchel is the second 20-game winner in the majors. The Chicago Cubs' Jake Arrieta won his 22nd on Friday.
Ruby De La Rosa (14-9) lasted three innings for the Diamondbacks.
Arizona committed a season-worst four errors that led to five unearned runs. The Diamondbacks' previous record for runs allowed was 20 at Colorado in 2003.
Peter O'Brien, a top Arizona prospect and a September call-up, hit a 471-foot shot into the picnic area in left field off Keuchel for his first big league home run.
"That was one of the bright spots tonight," Hale said. "We had four pinch hitters and four hits and we won the fifth and the ninth (innings) and we got tacos for the fans and fireworks (after the game). There was a lot of fireworks during the game. Unfortunately none were shot off by our bats."
Fans cheered when the fifth run scored in the ninth because that meant a taco giveaway at local Taco Bells.
Errors by Arizona third baseman Aaron Hill and left fielder Yasmany Tomas cleared the way for five runs in the first two innings. The Astros built a 10-2 lead through six, then entered club-record territory with a seven-run seventh and four-run eighth.
Springer's head-first slide just beat right fielder Socrates Brito's throw at the plate for a run in the first. Twenty more followed.
Houston improved to 15-3 in interleague games, 7-1 on the road.
In case of a play-in game for the wild-card berth, Houston would travel to Minnesota if it's the Twins; the Astros would be home if it's the Angels. Houston last made the postseason in 2005.
Astros: OF Carlos Gomez sat out with sore ribs.
Diamondbacks: OF Ender Inciarte was out of the lineup after hitting a ball off his shin Thursday night. OF David Peralta injured his right wrist diving for a ball Thursday night. An MRI was negative but he did not play.
Astros: RHP Collin McHugh (18-7), the second half of Houston's potent 1-2 pitching duo, tries to clinch the Astros at least a tie for the wild-card berth.
Diamondbacks: RHP Jeremy Hellickson (9-11) makes his final start of the season for Arizona.
