HOUSTON -- The Houston Astros' penchant for late-inning rallies continues to underscore just how little attention they pay to strikeouts, instead focusing on the belief in their ability to string together quality at-bats.

Left-hander Dallas Keuchel pitched seven innings without allowing an earned run and designated hitter Evan Gattis bashed a tiebreaking, two-run homer in the sixth inning as the Astros won the rubber match of their series with the Oakland Athletics, 6-1 on Wednesday at Minute Maid Park.

Keuchel (6-0) allowed six hits and two walks while striking out four. His ability to induce ground balls again served as his greatest weapon, enabling Keuchel to pitch around traffic whenever trouble arose.

Despite retiring the Athletics (14-28) in order only three times, Keuchel kept the Astros in position to surge ahead with 14 ground-ball outs. He allowed two baserunners in the first inning and loaded the bases in the fourth without permitting a run in either frame.

"Man, I felt like I had to fasten my seatbelt pretty early on," Keuchel said. "Just tried to hang in there, but credit the defense for making some huge plays. That's major league baseball right there. That's a quality team, very resilient, and I'm just happy to be out there today."

Oakland scratched across an unearned run on a two-out fielding error by Astros first baseman Chris Carter in the sixth, but Keuchel closed that inning with a ground-ball out and got two more in succession after Athletics second baseman Eric Sogard opened the seventh with a single to center field. Keuchel struck out right fielder Josh Reddick to cap the seventh and complete his outing.

"I was watching some stats on Keuchel; and, when he gets into a situation like that with bases loaded, a guy like him has the ability to get out of it because he gets so many ground balls," said Athletics designated hitter Billy Butler, who finished 1-for-1 with two walks against Keuchel. "That's the one thing you want to do in that situation, and he seems to get them all of the time. You've got to give him credit on that."

The Astros (27-14) mustered just one run and two hits against Oakland right-hander Jesse Hahn (1-4) before Gattis delivered with two outs in the sixth. Right fielder George Springer initiated the rally with an opposite-field single to right before Gattis whacked his eighth home run of the season 414 feet to left field as Houston grabbed a 3-1 lead.

"He went toe-to-toe really," Athletics manager Bob Melvin said of Hahn. "It was just one pitch that was down in the zone and Gattis went down there and got it. Other than that, I thought he was going toe-to-toe with Keuchel. I thought he pitched great today."

The Astros tacked on three runs and five hits in the eighth, with Carter finding some redemption via a two-run single that rewarded Springer for his hustle double on a broken-bat liner behind first base. Houston leads the majors with 73 runs scored in the seventh inning or later, and he improved to 24-0 when scoring at least four runs.

"Our offense is confident enough to know that if we hang in there enough somebody is going to do something," Astros manager A.J. Hinch said. "And then once somebody does that, that one thing, it seems to propel everybody else to have good at-bats and continue some innings.

"It's not that we can't be shut down; we've faced some pretty good pitching. But we can be pretty tough on the opponent once we break through with the big hit."

NOTES: Oakland placed LHP Drew Pomeranz on the 15-day disabled list with a sprained left AC joint. Pomeranz (2-3, 4.40 ERA) left his start in the fifth inning Monday night with shoulder tightness. The Athletics recalled RHP Arnold Leon from Triple-A Nashville. ... While the team travels to Detroit, Astros LHP Brett Oberholtzer will remain in Houston and throw a bullpen session on Thursday. Oberholtzer was placed on the 15-day disabled list on May 13 with a left index finger blister. The club will make a decision on a potential rehab assignment based on the results of his bullpen. ... Athletics LF Coco Crisp is day to day with neck tightness. He departed in the fourth inning Tuesday night after feeling discomfort and will remain under evaluation.