"We're going to attack these guys," the right-hander said.
The strategy worked to perfection, as Fister pitched seven strong innings and Jose Altuve continued his torrid hitting as the Houston Astros defeated the A's 7-0.
Fister (10-6) struck out five and allowed four hits and two walks as he continued his mastery of Oakland. He's 3-1 with a 0.99 ERA in four starts against the A's this season.
"Seeing them a lot, they know what we do and we know what they do," Fister said. "It just comes down to execution, and I was going to fill the zone up."
The A's, who had won four of five since the All-Star break and took their second straight series, failed to advance a runner past second base against Fister.
They moved just three runners into scoring position (one on a two-base error).
"Obviously his repertoire matches up OK with these guys but it's still about executing pitches," Astros manager A.J. Hinch said.
"When he executes it really doesn't matter what the other lineup is."
Altuve was 2 for 3 with two walks. Baseball's leading hitter is 12 for his last 17 in his last four games.
"He's really the centerpiece of our lineup now that he's batting third, in the sort of famous position that baseball loves," Hinch said, noting that Altuve's improving in every area, including his leadership.
"He's a truly a superstar in this game that I think more people are getting to know the more we play well."
The Astros, who had lost three of four, scored two runs in the second with two outs and nobody on base when five batters reached safely against A's starter Daniel Mengden (1-5).
Mengden struck out five and allowed three runs, five hits and five walks in five innings. He recovered from a shaky start, blanking the Astros over the last three innings.
"He's still trying to find his rhythm again," A's manager Bob Melvin said of Mengden. "It was better the last couple of innings, but command has been his issue. Basically with all (four of) his pitches we saw him really fine.
"I think he's getting behind and still trying to jam all four pitches in there as opposed to trying to establish one or two early. Certainly when everything is going well it's easy to do. When it's not maybe you have to simplify a little bit."
Fister is 9-3 over his last 15 starts going back to May 1. The Astros are 12-3 over that stretch.
Carlos Correa, who's settling into his role as the Astros' cleanup hitter, was 1 for 2 with three walks and three RBIs.
The Astros and A's rank at or near the bottom in virtually every meaningful offensive category out of the designated hitter's spot. The Astros' .186 and the A's .205 batting averages going into Wednesday were the league's two worst. The A's DH's were tied with the Chicago White Sox with the fewest home runs (8) and alone at the bottom with 33 RBIs. Houston's DH's ranked third- and fourth-worst in the league with 38 RBIs and 11 home runs.
Astros: DH Evan Gattis was pulled after getting hit by a pitch in the right hand in the fifth. X-rays were negative and Gattis said he's day to day "but no fracture."
Athletics: LHP Rich Hill, removed five pitches into his last start on Sunday after a blister on his left middle finger burst, is doubtful for Sunday's game against the Tampa Bay Rays, the next open spot in the A's rotation with Overton's demotion, Melvin said.
Astros: RHP Lance McCullers pitches a series opener against the Los Angeles Angels on Friday. McCullers has lost three of his last four decisions. He's 1-1 with a 2.35 ERA in five career starts against the Angels, allowing one run in a 5 2/3 innings in his only start against the Angels this season.
Athletics: RHP Sonny Gray (4-8, 5.12) snapped a career-worst seven-game losing streak in his most recent start and will hope to build on that momentum on Thursday against the Tampa Bay Rays. Gray is 2-1 with a 3.11 ERA in six career starts against the Rays and 2-2 with a 7.01 ERA in five starts against the Eastern Division this year.