In a game they needed to keep their fading American League West hopes alive, the Astros were plagued by misplays and mistakes as their tough road trip continued by watching the A’s celebrate a walk-off win on Wednesday night.

Ramón Laureano hit a walk-off single to left-center field off Ryan Pressly in the bottom of the ninth inning to lift the A's to a 3-2 win over the Astros at the Coliseum. Houston now trails Oakland by 5 1/2 games in the AL West, which the Astros have won the previous three seasons.

• Box score

“Man, that’s tough,” Houston manager Dusty Baker said. “We kind of gave that game away.”

The Astros are 3-6 against the A’s this year, dropping the season series against them for the first time since 2014. Houston has one final head-to-head chance to slash into Oakland’s division lead in Thursday afternoon’s five-game series finale. The Astros are 1-7 so far on their season-long 11-game road trip.

“We take the same mentality every series, but when it’s against the Astros, you can tell our game goes a little higher,” said A’s starter Jesús Luzardo, who allowed two runs in seven innings. “I think we’re in a great spot. Our mentality is great, and the vibe in the clubhouse is great. We’re just trying to keep this thing going.”

The Astros entered the seventh with a 2-0 lead on the strength of a George Springer home run to lead off the game, a Yuli Gurriel solo shot in the sixth and a strong first career start for Luis Garcia (one hit allowed in five scoreless innings). That's when things went awry.

With runners on first and second (both reaching via walks) and two outs in the seventh, Tommy La Stella hit a shallow fly ball to left field off reliever Josh James. Kyle Tucker ran toward the line and tried to make a backhanded catch as he slid, but the ball missed his glove, caromed off his leg and rolled into the A’s bullpen. The two-run double tied the game.

“It looked like Tucker had caught that ball, and the next thing I know, the ball is rolling around in the bullpen,” Baker said. “That was the first downer. Like I said, we just gave that game away to them.”

Even Tucker thought he should have made the play to end the inning.

“Yeah, it was close,” Tucker said. “It kicked off me and all the way into their bullpen. Two runs scored. That’s a ball I should have caught.”

In the ninth, Pressly walked Sean Murphy and hit Tony Kemp to open the inning, setting the stage for Laureano -- a former Astros prospect -- to wallop a game-winning single into left-center field. The Astros walked seven batters in the game, including Murphy, the No. 8 hitter, three times.

“This is a prime example that walks will definitely haunt you,” Baker said. “It rolls their lineup around and you’re facing guys you wouldn’t ordinarily have to face. When you walk them, you have no chance of getting them out. We’re pitching Murphy like he’s Johnny Bench or something. It’s very debilitating.”