Not even the return of Alex Bregman from a right hamstring injury that had sidelined him for three weeks or a clutch game-tying homer by Michael Brantley was enough to get the Astros out of their tailspin.

The A’s continued their domination over the Astros at the Coliseum by getting to starter Zack Greinke in the sixth inning -- one inning after Brantley’s game-tying homer -- to send Houston to its sixth consecutive loss, 4-2, in the first seven-inning game of Tuesday’s doubleheader.

• Box score

“It’s deflating,” Astros manager Dusty Baker said. “I mean, everything is going to the opposition’s way right now. Like I said yesterday, nothing lasts forever. Just seems like it.”

The Astros dropped to .500 (21-21) and to 0-6 on their 11-game road trip through Anaheim, Oakland and Los Angeles. They’re 5 1/2 games behind the first-place A’s in the American League West with 18 games remaining.

“It doesn’t matter,” said Greinke, who passed David Cone for 25th on the all-time strikeout list with six K's on Tuesday. “Everyone makes the playoffs. We’ll be all right still. If we don’t make the playoffs, then we don’t deserve to make the playoffs.”

Greinke allowed a season-high four earned runs in six innings, while Houston has scored just seven runs in five games in Oakland this year (0-5). Greinke lamented a third-inning homer to Khris Davis, who also hit an RBI double off the righty in the sixth, and Greinke struggled to solve Ramón Laureano, who had an RBI single in the third and leadoff double in the sixth.

“That’s what’s frustrating,” Greinke said. “I felt really good. My mind was thinking properly. I just made a couple of mistakes. I don’t know. I should have done better than I did. Just a good job by them, a couple of their guys. Khris Davis hit some pitches I wanted to make to him, and I made some mistakes to Laureano. Those two guys, I feel like, were the biggest issue.”

Greinke is the most recent Houston starter to win a game, which came Thursday in Houston against the Rangers. The Astros’ rotation has an 8.17 ERA in six games on the road trip.

Greinke breezed through the first two innings on 20 total pitches, but he needed 36 to get through the third alone.

“He was great,” Baker said. “He started out great and had the long inning in the third. He had 30-odd pitches and before that had a very, very low pitch count. They fouled off some pitches and got his pitch count up. … He gave us a chance to win.”

A’s starter Frankie Montas held the Astros to two runs over five innings and hinted how loose his team is playing against the defending AL champions.

“I don’t think any of us are thinking about the pressure the Astros have,” he said. “That’s their job, to think about if they have pressure or not. We’re chilling over here. Just trying to play good baseball.”