OAKLAND -- The Astros could only remain undefeated against the A's for so long.

After winning the first five games against its divisional rival to open the season, Houston mustered up just four hits in a 3-1 loss at the Coliseum on Saturday, setting up a rubber game in Sunday's series finale.

It was an uncharacteristic offensive showing for the Astros, who lead the Majors with a .263 batting average and rank fifth overall with a .750 OPS. It was the eighth time this season that they were limited to four hits or fewer, and they've lost all but one of those games.

Mauricio Dubón, who got his second start at first base this season in order to get his hot bat in the lineup, reached in all three of his trips to the plate and has now hit safely in his last four games with at least one plate appearance, going 8-for-13 in that span. Saturday, he singled twice and capitalized on a wild throw from A's shortstop Max Schuemann that resulted in a two-base error in the sixth -- and came around to score the lone (unearned) run charged to A's starter JP Sears.

But that was all the run support Houston could manage to back starter Spencer Arrighetti, the club's No. 3 prospect per MLB Pipeline, who was charged with the loss after allowing three runs over five-plus innings.

"We just couldn't get anything going offensively," manager Joe Espada said. "Four hits, two of those by Dubón, and I felt like Sears just kept us off balance. He had that sweeper working today."

The heavy sweeper usage was part of Sears' game plan. He threw 32 of them on Saturday for 47% of his 68 pitches. It was his highest percentage of sweepers thrown since he last faced the Astros on May 14 (36%) at Minute Maid Park.

Making his sixth career appearance against Houston, Sears drew on a combination of research and prior experience when deciding how to best attack its hitters.

"They’re a pretty aggressive lineup," Sears said. "I saw that last night and have seen it throughout the season. I think it just gives them a little bit of a different look. They kind of have to honor the slider always, and it makes my fastball better when I want to use it."

When the Astros last saw Sears in Houston, in an eventual 2-1 win in 10 innings, the lefty tossed five frames of one-run ball. He struck out two and mostly pitched to contact, getting two groundouts and six flyouts.

This time around, the contours of Sears' approach against Houston were largely the same. There wasn't much swing-and-miss to speak of, as Astros hitters whiffed only twice on 33 swings against him.

The contact didn't translate into hits, as Sears got seven groundouts and seven flyouts on Saturday. Houston had an average exit velocity of 86.8 mph against Sears, and three of the team's four hard-hit balls (95 mph or higher) against him turned into outs.

"He was locating pretty good," said shortstop Jeremy Peña, the only Astro other than Dubón to reach scoring position after he singled in the seventh and advanced on a groundout. "He was just inducing outs. We were putting the ball in play, weak contact all over. That's what pitchers do."

Said Espada: "We hit a few balls hard … right at people. I just thought that he kept us kind of off balance. We couldn't really get our groove going and our timing down against him."

When Sears exited after six innings, Oakland's bullpen didn't prove much easier to face. The Astros had just two additional baserunners in the final three frames, with A's rookie closer Mason Miller striking out the side in the ninth.

Outside of Friday's six-run fourth inning capped by Jake Meyers' three-run blast -- in which the Astros batted around, sending 11 hitters to the plate -- Houston has not made a lot of noise against Oakland pitching in the first two games of the weekend series.

The A's held the Astros off the board starting from the fifth on Friday up to the sixth on Saturday, when Kyle Tucker's sacrifice fly to right field plated Dubón, a span of 10 scoreless innings.

"I feel like we didn't really produce," Peña said. "We didn't really get anything going. That's pretty much how the day went."