Stephen Piscotty, Matt Chapman power A’s in 7-5 win over Mariners

Seattle Mariners pitcher Mike Leake (8) meets with pitching coach Mel Stottlemyre, left, during the first inning of a baseball game against the Oakland Athletics on Friday, Aug. 31, 2018, in Oakland, Calif. (Ben Margot / AP)
Oakland Athletics' Matt Chapman, right, is congratulated by third base coach Matt Williams (4) after hitting a home run off Seattle Mariners' Mike Leake during the first inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (Ben Margot / AP)
Oakland Athletics' Stephen Piscotty, right, is congratulated by Matt Olson (28) after hitting a two-run home run off Seattle Mariners' Mike Leake during the first inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (Ben Margot / AP)
Seattle Mariners' Robinson Cano celebrates after hitting a home run off Oakland Athletics' Mike Fiers in the fourth inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (AP Photo/Ben Margot) ORG XMIT: OAS108 (Ben Margot / AP)
Seattle Mariners' Nelson Cruz, rear, celebrates with Kyle Seager (15) after hitting a home run off Oakland Athletics' Mike Fiers in the fourth inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (AP Photo/Ben Margot) ORG XMIT: OAS111 (Ben Margot / AP)
Seattle Mariners' Ryon Healy, center, celebrates with Dee Gordon, right, as Robinson Cano (22) watches after Healy hit a two-run home run off Oakland Athletics' Mike Fiers during the fourth inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (AP Photo/Ben Margot) ORG XMIT: OAS112 (Ben Margot / AP)
Seattle Mariners' Mike Leake (8) waits for Oakland Athletics' Stephen Piscotty to run the bases on a two-run home run during the first inning of a baseball game Friday, Aug. 31, 2018, in Oakland, Calif. (Ben Margot / AP)

OAKLAND, Calif. – Stephen Piscotty and Matt Chapman homered, Matt Olson had three hits and the Oakland Athletics defeated the Seattle Mariners 7-5 on Friday night.

Oakland pulled 1 1/2 games behind first-place Houston – which lost to the Los Angeles Angels – in the A.L. 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 4 2/3 innings of scoreless relief after Mike Fiers was rocked in his shortest outing of the season.

Yusmeiro Petit (6-3) pitched 1 1/3 innings for the win.

Blake Treinen worked a scoreless ninth for his 34th save after Fernando Rodney, Lee Trivino and Jeurys Familia each pitched one inning.

Olson singled leading off the fifth and scored the go-ahead run on Ramon Laureano’s sacrifice fly.

The A’s extended their lead to 7-5 in the sixth when Khris Davis singled in Jed Lowrie.

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.

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.

Mariners shortstop Jean Segura was out of Friday’s lineup with a deep bone bruise in his left shin. He suffered the injury fouling a ball off his leg on Wednesday in a game against San Diego.