A day after their lowest attendance for a home opener without coronavirus restrictions in more than 30 years, the A's drew a crowd of 3,748 - the smallest with fans at the Coliseum since 3,180 attended a 6-4 loss to the Chicago White Sox on Sept. 25, 1980.
Elvis Andrus and Christian Bethancourt both had two hits and scored to help Oakland to its seventh win in 10 games after an 0-2 start. The A's also got a lift from their bullpen, as four relievers combined for four shutout innings.
"Outstanding job by our bullpen again," rookie manager Mark Kotsay said. "The mentality down there is 27 outs and it kind of showed itself tonight. A really fun night for us overall. Didn't swing the bats great but we scored one more than they did, so good outcome."
Anthony Santander and Trey Mancini each had two hits for the Orioles, whose $48 million payroll is last in the majors. The A's are 29th at $58 million.
Brown, who threw out a runner at home from right field a night earlier, came through at the plate. After Bethancourt singled and Andrus walked, Brown lined an 0-1 pitch from Mike Baumann (1-1) into right-center.
Pache, part of the trade that sent two-time Gold Glove first baseman Matt Olson to the Braves, added to a growing list of stellar plays he's made for the A's while outfielder Ramon Laureano serves the remainder of his 80-game suspension for testing positive for a banned substance, which extended through the first 27 games of this season.
"He's defensively changing games right now," Kotsay said.
Pache robbed Kelvin Gutiérrez of a hit in the second inning when he crashed into the center-field fence as the ball popped out of his glove, then reached out and caught the ball while tumbling to the turf. Gutiérrez was nearing second base and slapped his left hand on his batting helmet in disbelief as Pache got up, smiled and flexed.
"The first thing that came to my mind was that I had to get that ball," Pache said through a translator. "That's how I like to play. I play hard, I play with all my heart. The coaching staff and the players, they continue to trust me. They have the confidence in what I can do and it brings a lot of emotion."
In the eighth, Pache ran down Austin Hays' deep fly to center and made the catch just before the wall.
"To be as young as he is, as confident as he is, gives us a nice spark to the team," said Zach Jackson, who earned his first big league save. "Every time that he's out there it feels like he's going to do something exciting."
Zach Logue retired four batters to win his major league debut. Jackson struck out Santander on a checked swing with a runner at first to end it.
The Orioles scored a run off Cole Irvin in the first. Santander singled, Ryan Mountcastle doubled and Mancini followed with an RBI grounder.
Chris Ellis threw 4 1/3 innings without allowing a run after being called up from Triple-A Norfolk before the game to start for the Orioles. The right-hander pitched around traffic for much of his outing, giving up four hits with three walks and two strikeouts.
Irvin, whose 15 losses led the American League in 2021, allowed six hits in five innings.
Orioles outfielder DJ Stewart was designated for assignment to make room for Ellis on the 40-man roster. RHP Marcos Diplán was optioned to Norfolk.
Athletics: 3B Kevin Smith is wearing a walking boot and will be evaluated for a possible leg injury following an awkward slide into first base Monday night. Kotsay was uncertain whether Smith will need to go on the injured list.
Orioles RHP Jordan Lyles (0-1, 5.23 ERA) has three wins in eight career appearances against Oakland. A's RHP Daulton Jefferies (1-1, 1.93) makes his fourth career start and first against Baltimore. Due to weather, the start of the game was moved up to 3:07 p.m.