OAKLAND,Calif. -- The Oakland Athletics blew a big early lead and recovered to pull out a big win.
Oakland pulled 1 1/2 games behind first-place Houston -- which lost to the Los Angeles Angels -- in the AL West, and extended its lead for the second wild card over Seattle to 5 1/2 games.
The A's have won 20 of their last 29 games and are 26-13 since the All-Star break.
The Mariners have lost four of their last five.
After squandering an early 5-0 lead, the A's scored the go-ahead run in the bottom of the fifth and then turned to their shutdown bullpen, which combined for 5 2/3 innings of scoreless relief after Mike Fiers was rocked in his shortest outing of the season.
"We've played a lot of games where things like that have happened," Olson said. "We know that things can go in our favor just as quickly as they can go the other way, so we don't get too down if it's going bad. We have confidence in ourselves."
Yusmeiro Petit (6-3) pitched 1 1/3 innings for the win.
As nice as the win was, A's manager Bob Melvin acknowledged that taxing his bullpen this much isn't a sustainable model.
"You can't do it every night, that's the issue," Melvin said. "Certainly we'll have some reinforcements tomorrow, but the reason we win the games like this is because of those four guys that we used and Petit was terrific tonight."
Olson singled leading off the fifth and scored the go-ahead run on Ramon Laureano's sacrifice fly.
Fiers gave up five runs in 3 1/3 innings in his worst start since coming to Oakland in a trade with the Tigers on Aug. 6.
"We knew we had to get on him early in the game, get back into it and our guys responded, which was great to see, but just not enough after that," Mariners manager Scott Servais said.
"Their bullpen was really good tonight."
Piscotty's 19th home run -- a two-run shot to left off Mariners starter Mike Leake -- highlighted a five-run first inning in which the A's sent nine men to the plate.
Chapman started the inning with his 22nd home run -- a solo shot to left -- and Olson had an RBI double.
Leake (8-9) gave up six runs and 11 hits with two walks in 4 1/3 innings. He lost his fourth straight decision and is winless in his last 11 starts.
Chapman also had a double in the fourth. He leads the majors with 22 extra-base hits in August.
The A's recalled outfielder Dustin Fowler from Triple-A Nashville on Friday. He was 0 for 5 in his first game back. ... Mariners RF Mitch Haniger extended his hitting streak to 12 games. ... The A's are 66-0 when leading after eight innings.
Mariners: SS Jean Segura was out of Friday's lineup with a deep bone bruise in his left shin. ... LHP Marco Gonzales (neck muscle strain) threw on flat ground for a second straight day on Friday, but it's not known when he'll throw a bullpen session, the next step in his recovery, manager Scott Servais said. Gonzales went on the DL Aug. 27, retroactive to Aug. 24.
Athletics: LHP Brett Anderson (left forearm strain) threw on flat ground on Friday.
Mariners LHP James Paxton (10-5, 3.68 ERA) will make his start since going on the DL with a left forearm contusion on Aug. 15. A's RHP Daniel Mengden (6-6, 4.28) is 0-2 with a 4.91 ERA in two career starts against Seattle.
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