SEATTLE -- Champagne will be on ice when the A’s return to T-Mobile Park for Friday night’s game against the Mariners.

In the driver’s seat with a one-game lead for the top American League Wild Card spot, the A’s are in a position to clinch a postseason berth for a second straight season in the same clubhouse they popped bottles inside of last September following Thursday’s 3-1 win over the Mariners, which trimmed their magic number to one.

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“We’ve been working hard for a long time and remember how fun it was last year,” A’s third baseman Matt Chapman said. “We didn’t forget that our postseason was shortened last year with that one opportunity. We’re excited to be in that spot again."

Chapman continued to show signs of an imminent hot streak by crushing his team-leading 36th homer, a two-run blast off Mariners starter Félix Hernández in the second inning. The homer set an early lead that the left-handed combo of Sean Manaea and Jesus Luzardo had no trouble holding onto with a dominant eight innings on the mound, with Liam Hendriks securing his 25th save of the year by turning in a scoreless ninth.

Notching their 17th win of September, the A’s tied their highest mark over a single month this season and also put themselves one win away from their 2018 win total of 97.

With the magic number now at one, the A’s don’t even need a win to lock up a postseason spot on Friday. If the Indians lose their game against the Nationals Friday afternoon, the A’s could clinch before they even take the field against the Mariners.

But even if they do secure a spot that early, Oakland still has incentive to keep winning in order to host the AL Wild Card Game on Wednesday night on ESPN, so the A’s will look to keep winning -- something they’ve done more than any other team in baseball for about four months now. Their .667 winning percentage since May 16 -- one day after they were swept in a two-game series in Seattle, coincidentally -- was the best in baseball entering Thursday.

“We’re not taking anything lightly,” Chapman said. “We’re not in it until we’re in it. We still have to take care of our own business. But we’re excited, and to be able to have a chance to host the Wild Card Game is awesome.”

A’s manager Bob Melvin’s confidence in Chapman never wavered as Chapman struggled over the past month, and the third baseman is showing why. Chapman entered Wednesday’s game against the Angels batting .123 in September, then he went on to homer Thursday for the second straight day. Perhaps it's a sign that he's heating at the right moment.

Similar to his blast at Angel Stadium on Wednesday night, Thursday’s homer was also a booming shot. Coming on a first-pitch sinking fastball from Hernández, it was smoked at 105.1 mph off the bat and traveled over the wall in center at an estimated 390 feet, per Statcast.

“I don’t want to get too far ahead of myself, but I feel a lot better than I did a few days ago,” Chapman said. “Just trying to keep trending in the right direction and help the boys win, because pretty soon here, it’s going to be do or die. Just doing whatever I can to get ready for the playoffs.”

Last season, the A’s struggled to find a reliable option on the pitching side for the AL Wild Card Game against the Yankees, ultimately deciding on Hendriks as an opener. Should the A’s be in a similar spot next week, the decision should be easier with the way Manaea and Friday’s starter Mike Fiers are pitching.

In his last start of the regular season on Thursday, Manaea continued to dominate as he has since returning on Sept. 1 from left shoulder surgery. Manaea made quick work of Seattle’s lineup, holding it to one run over six innings with five strikeouts, recording three with his signature slider.

The velocity may not be flashy -- his fastball topped out at 92.4 mph -- but Manaea has been making up for the lack of velocity with command. He didn't issue a walk against Seattle, and in five starts this season, Manaea has allowed just four earned runs over 29 2/3 innings (1.21 ERA) with a 30-to-7 strikeout-to-walk ratio.

“The fastball and changeup have always been there. It’s the slider that has made him a true three-pitch guy,” Melvin said. “Different velocities on all of them, which makes his fastball play up because of that. He continues to get better and better. Every start this year, he’s been fantastic.”

Farewell to Félix

With Hernández making his final start of the season and likely his last as a Mariner, watching the right-hander be celebrated at T-Mobile Park was a special moment for young A’s pitchers. Luzardo, who idolized Hernandez growing up as he tried to emulate some of his movements, was particularly moved.

“It was definitely special. It was a surreal feeling,” Luzardo said. “I grew up watching him. I didn’t even tear up when I debuted or got called up, but I teared up in the bullpen watching [Félix]. It was a crazy feeling."