HOUSTON -- Of all the losses the Astros have endured this year, this one defied the most logic.

Coming off a 12-run outburst against the Padres a day earlier, the Astros were shut down by three Oakland pitchers and forced to digest a 4-0 defeat to the 99-loss A's on Monday night at Minute Maid Park. Houston had won nine of its first 10 games against Oakland this year.

According to STATS, it’s the first time in MLB history a team at least 50 games under .500 shut out the defending World Series champions on the road.

“Any time you lose isn’t great, but [the A’s] pitched really well and played good defense behind them,” Astros right fielder Kyle Tucker said. “They just did a really good job tonight.”

• Games remaining: vs. OAK (2), at KC (3), vs. BAL (3), vs. KC (3), at SEA (3), at AZ (3).
• Standings update: The Astros (82-63) lead the American League West by two games over the Rangers (79-64). Houston is in line for the No. 2 seed in the AL, meaning it would bypass the Wild Card round.

The Astros, who entered Monday having scored the most runs in the Major Leagues since the All-Star break, were held to one hit through the first eight innings -- a single in the first by Jeremy Peña. In the 20 games prior to Monday, Houston averaged 7.4 runs and 11.8 hits per game.

A's opener Mason Miller threw two scoreless innings, and lefty reliever Ken Waldichuk followed with six hitless frames against a lineup that typically bashes southpaws. The Astros entered slashing .279/.346/.481 against lefties this year. Houston managed two hits to open the ninth before closer Trevor May completed the shutout.

“It wasn’t necessarily our offense; it could have been their pitching,” manager Dusty Baker said. “The first guy, really, I don’t think we had ever seen him, and he was throwing 100. They switched to a guy that was completely the opposite. Sometimes that opener works.”

Miller threw 11 pitches that were at least 100 mph and topped out at 101.4 mph. He was pulled at 45 pitches because he was on a 50-pitch limit. Enter Waldichuk, who retired 17 of the 19 batters he faced without giving up a hit.

“Waldichuk, he was changing speeds -- high fastball, a lot of changeups,” Baker said. “We were in the fourth or fifth inning, it seemed like, before we could spit. They threw a good game against us. It doesn't matter who you’re playing if a guy is dealing on the mound out there. And that’s what they were doing. They pitched a hell of a game against us.”

Entering the ninth inning, 14 of the 15 hardest-hit balls of the game belonged to the A’s, with the lone exception a 98.4 mph flyout by Astros catcher Martín Maldonado in the sixth inning. Jose Altuve and Peña began the ninth with singles, and Yordan Alvarez hit a 114.1 mph rocket right at Seth Brown in right field. The ball had an expected batting average of .770 but was instead an out. It was that kind of night for Houston.

“We had an opportunity. It looked a little promising,” Tucker said. “We still [would have] had to put up four runs against a good pitcher, but just as long as we try and grind together at-bats and at least have opportunities, we’re always still in games. It just didn’t work out tonight.”

Astros starter Framber Valdez worked seven innings and gave up three runs, including solo homers to Brent Rooker in the second inning and Shea Langeliers in the seventh. He struck out 10 batters -- his most since whiffing 13 against the Angels on July 15.

“Framber threw good enough to win,” Baker said. “You get shut out, it doesn’t matter. You give up a couple of solo home runs, and usually that doesn’t hurt you. He had a number of strikeouts. He threw the ball well, but their pitching shut us down.”