OAKLAND, Calif. -- With the September stretch run under way, the Oakland Athletics want to leave nothing to chance when it comes to their playoff hopes.
Splitting a four-game series and staying well ahead of the Seattle Mariners mattered so much with both clubs in contention.
Stephen Piscotty homered twice and matched his career high with five RBI as the A's widened their lead over the Mariners for the second AL wild-card spot, beating them 8-2 Sunday. Oakland moved 5 1/2 games ahead of Seattle.
"This is probably one of the biggest wins that we've had all season," pitcher Edwin Jackson said. "It was definitely a must-win game."
Jackson (5-3) allowed one run on three hits in six innings. He improved to 5-0 with a 1.30 ERA in five career starts against the Mariners.
Seattle starter Felix Hernandez (8-13) is 0-7 over nine outings since beating the Royals on June 30.
A day after the Mariners held on for an 8-7 win, they took a 1-0 lead into the fifth before Piscotty tied it with a solo shot. He added a sacrifice fly in a four-run sixth.
"Disappointing way to finish the series," Mariners manager Scott Servais said. "Big win last night, obviously big sway game today, where we're at in the standings if you could pull this this one out, but we didn't get enough going offensively to make that happen."
Piscotty hit his 21st homer, a three-run drive, in the eighth for his third career multihomer performance.
"I feel like everything's kind of rolling my direction right now, which is good," Piscotty said. "I was glad I was able to kind of jump start that."
Marcus Semien's go-ahead, two-run single in the sixth chased Hernandez.
Hernandez retired the first seven hitters in order before Chad Pinder's one-out single in the third. The right-hander then got two consecutive inning-ending double plays to face the minimum through four.
"It just shows the kind of perseverance in our team," Jackson said. "It shows the kind of fight that we have."
Hernandez allowed four runs and four hits in five-plus innings, struck out three and walked two. He has made a minor mechanical change and had been commanding his fastball better, though he threw two wild pitches in the costly sixth.
The A's bounced back a day after striking out 18 times. On Saturday, manager Bob Melvin used an Oakland-record 24 players for a nine-inning game and nine pitchers -- a franchise high for nine innings.
Seattle leadoff man Mitch Haniger opened the game with a double for a career-best 14-game hitting streak. Khris Davis, who hit his majors-leading 40th homer Saturday night for the A's, went 0 for 4 with two strikeouts.
The A's on Monday will remember Piscotty's late mother, Gretchen, who died in May, as well as Hall of Famer Catfish Hunter and others affected by ALS in an ALS Awareness Day. The team is donating $150,000 to ALS Therapy Development Institute.
"I've said many times he's got a big angel on his shoulders," Melvin said of Piscotty.
This lopsided result isn't a common occurrence when these teams play each other. Of their 16 matchups this season, eight have been decided by one run and three more by two runs. They have one series remaining, at Safeco Field from Sept. 24-26 during Oakland's final road trip.
Mariners: DH Nelson Cruz played through a sore left foot and hobbled on the basepaths a day after a foul ball got him. ... LHP Marco Gonzales, on the disabled list retroactive to Aug. 24 with a strained neck muscle, was tentatively scheduled to pitch off a mound Monday in a light bullpen session. "I'm much more encouraged based on what the trainers have told me the last couple days," Servais said.
Athletics: RHP Andrew Triggs (nerve irritation in his pitching arm) threw a 30-pitch, two-inning simulated game Saturday and said he "felt great." While Melvin said Triggs would be re-evaluated to determine his next step, the pitcher expects to have a rehab outing Wednesday at Class A Stockton. ... LHP Brett Anderson (strained pitching forearm) threw on flat ground Sunday and could work off a mound as soon as Monday.
LHP CC Sabathia (7-5, 3.36 ERA) pitches back home in the Bay Area looking for just his second victory in eight starts when the New York Yankees -- who hold the top AL wild-card spot -- visit for a three-game series that begins with an afternoon contest on Labor Day. RHP Trevor Cahill (5-3, 3.60), 4-0 with a 0.85 ERA in eight home starts, pitches for the A's needing four strikeouts to reach 1,000 for his career.
Seattle returns home to host Baltimore, with RHP Erasmo Ramirez (1-3, 6.28) pitching Monday's series opener.
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