DENVER -- The Houston Astros hit two more home runs, including a three-run shot by pinch-hitter Domingo Santana, to beat the Colorado Rockies 8-4 on Thursday and sweep both two-game series this week between the clubs.

Santana hit his first career home run with one out in the eighth inning to give the Astros a five-run lead. Colorado's Scott Oberg surrendered the opposite-field homer to right on a 2-1 curveball, the eighth home run he has allowed in 24 1/3 innings this season.

"I was looking for a heater away," Santana said. "He hung me that curveball and I saw it pretty good. I was telling myself, 'Look for the pitch up.' And I saw it up and I took a good swing at it."

Santana went 0-for-17 last year with the Astros in his first six games in the big leagues. They recalled him on Tuesday when outfielder Colby Rasmus went on the bereavement list.

Santana was able to savor his first hit in the majors by going 1-for-3 on Tuesday. Now he can relish trotting around the bases after hitting his first home run.

"I couldn't even feel my footstep," Santana said. "I feel like I was flying, and it was pretty emotional."

Rockies pitchers logged 17 strikeouts, tying a franchise record set in a 22-inning game in 2008 and establishing a record for a nine-inning game. Fifteen of the strikeouts were swinging, which is no surprise because the Astros lead the majors with 627 strikeouts, an average of 9.2 per game.

But Houston also leads the majors with 97 homers and have won all 27 games this season when they have hit multiple home runs. They hit 12 in their four victories over the Rockies, including wins on Monday and Tuesday in Houston.

"That club's a bit of an enigma," Rockies manager Walt Weiss said. "They have a lot of power, a lot of athleticism, a lot of swing and miss. They have a real good bullpen and starting pitching. That's why they win games."

After left fielder Preston Tucker, who had three RBIs, hit a solo homer in the first, Astros starter Colin McHugh gave up a three-run homer to right fielder Carlos Gonzalez in the bottom of the inning.

McHugh (7-3) then allowed just two singles while stringing together five straight scoreless innings, leaving after throwing 112 pitches and issuing a career-high tying five walks. But the only one of those batters who scored was second baseman DJ LeMahieu on Gonzalez's home run.

"I kind of was able to find my four-seam fastball a little bit more up in the zone, just to be able challenge guys a little bit better," McHugh said. "But all day they got on base until the fifth. I think it was the first clean inning I had."

The Astros, who are 8-1 in interleague play this season, have won five straight games and six of their past seven.

The loss was the fourth straight and eighth in nine games for the Rockies, who tied a season high by falling 10 games below .500 at 28-38. They dropped the first two games of an eight-game homestand to fall to 13-20 at Coors Field, the second-worst home record in the National League this year.

"We have to dominate at home," Gonzalez said. "That's how it's been in Rockies history. If we play decent on the road and you dominate at home, you have a chance to go to the postseason. If you don't, you don't have a chance."

Rockies starter David Hale (2-2) tied his career high with nine strikeouts but threw 96 pitches and worked a season-low five innings. He yielded a career-high 10 hits and gave up five runs, the final two in the fifth when the Astros went ahead 5-3 on back-to-back doubles by Tucker and first baseman Chris Carter.

The Astros, who continue their eight-game trip with divisional games at Seattle and the Los Angeles Angels, scored eight runs in each of their final three wins over the Rockies, the last three runs coming on Santana's memorable swing.

"That was such a great moment for our team and for Domingo," Astros manager A.J. Finch said, "to come off the bench and contribute like that in a big spot where we could open up the game a little bit and get some confidence."

NOTES: Third-base umpire Bob Davidson left the game in the third inning because of dehydration. ... Astros CF Jake Marisnick left the game in the eighth with left hamstring discomfort. ... Rockies RHP Brooks Brown (right shoulder inflammation) was placed on the 15-day disabled list retroactive to Wednesday. The same injury put him on the disabled list last month. ... Rockies RHP Christian Bergman was recalled from Triple-A Albuquerque, one week after being optioned there, and pitched a scoreless ninth... RHP Rafael Betancourt (vertigo symptoms) is scheduled to throw 20-25 pitches to hitters Friday for the first time since going on the disabled list June 8. ... Astros OF Rasmus might return Saturday. He went on the bereavement list Tuesday after the death of his grandmother. ... Astros RF George Springer extended his hitting streak to 11 games, tying his career high. ... Astros SS Carlos Correa set a franchise record with 14 hits in his first nine major-league games. The old record of 13 was set by Ken Caminiti in 1987. Caminiti also held the previous record of 13 hits in his first 10 games.