SEATTLE (AP) - The Oakland Athletics clinched their first playoff berth since 2014, then beat the Seattle Mariners 7-3 Monday night behind Khris Davis' major league-leading 46th home run.
Jonathan Lucroy, Jed Lowrie and Matt Chapman also homered for the A's, assured no worse than a wild-card berth.
Oakland was one out into the game when Tampa Bay was eliminated with a 4-1 loss to the New York Yankees. The A's went on to win after Chapman broke a 3-3 tie with a two-run drive in the seventh off Shawn Armstrong (0-1).
Coming off three straight last-place finishes in the AL West, the A's (95-62) are 4 1/2 games behind AL West-leading Houston. They trail the Yankees by 1 1/2 games for home-field advantage should they meet in a wild-card matchup.
Robinson Cano and Dee Gordon homered for the Mariners.
Few predicted the A's could make the playoffs this season, a young team with few proven stars and a team that was 75-87 a year ago. Oakland won only 68 games in 2015 and 69 in 2016. The A's have the third-lowest payroll among the 30 major league clubs at $78 million for their 40-man roster, ahead of only the White Sox and Rays.
Oakland was 34-36 and 11 games behind Seattle in the wild-card on June 15. The A's have gone 61-26 since.
"We've had some younger players mature and become, for me, stars," Oakland manager Bob Melvin said Monday before the game. "I think the two guys on the corners (third baseman Matt Chapman and first baseman Matt Olson) should win Gold Gloves.
"Our defense is night-and-day to what it was and it's gotten better as the year's gone along. We've gone from last year being one of the worst defenses in the league to now one of the best. Our bullpen has been a strength for us all year. We don't just rely on one facet. We seem to be able to win in different ways."
One big contributor is Davis, the team's designated hitter, with 120 RBIs. Davis has hit at least 40 homers and driven in over 100 runs in each of this three seasons with the Athletics.
Blake Treinen, who pitched a perfect ninth inning , is 9-2 and one of the top closers in baseball this season with 37 saves and a 0.81 ERA, the lowest of all major-league relievers with at least 75 innings pitched. Opponents have a .091 batting average against Treinen this season with runners in scoring position.
"It's amazing," Melvin said. "Not only is he doing it closing games, he's doing in game when we're tied and he's pitching two innings at times. The numbers are absolutely fantastic. I don't know that I've seen numbers like that from any closer in quite some time. He's meant a lot to this team."
The A's are the only team in the majors with an undefeated record this season when leading after seven innings (68-0) and have the best record in one-run games at 31-13.
Oakland made key moves to bolster the pitching staff via trades over the summer by adding veteran relievers Juerys Familia and Fernando Rodney and starter Mike Fiers, who is 5-1 with a 2.90 ERA since joining the Athletics.
The A's overcame losing key starters from their rotation down the stretch. That included left-hander Sean Manaea, who pitched a no-hitter on April 21 against Boston and is done for the year recover from arthroscopic shoulder surgery that took place this past week.
The Athletics will be making their fourth playoff appearance in the last seven seasons, all under Melvin, and their 27th overall. The A's lost at Kansas City 9-8 in 12 innings in the 2014 wild-card game, the last time Oakland reached the postseason.
The last time the A's reached the World Series was 1990, losing in four games to Cincinnati. Oakland won the 1989 World Series after the Bay Area earthquake, sweeping San Francisco.
Athletics: Oakland starting pitcher Daniel Mengden was on the ground writhing in pain when he took a liner off his right foot that was hit by Denard Span. Mengden was on the ground for about five minutes, but got up and surprisingly stayed in the game. LHP Ryan Buchter (5-0) got two outs, and three more relievers completed a six-hitter.
Mariners: LHP James Paxton, making his first start since Sept. 7 after a bout with pneumonia, allowed two runs - both on homers- and three hits. He left after four innings and 71 pitches because he was on a pitch count.
Athletics: LHP Brett Anderson (4-5, 3.96 ERA) will make his third start Tuesday since coming off the 10-day DL (strained left forearm) on Sept. 13. Anderson is 1-1 with a 3.60 ERA since coming off the DL.
Mariners: RHP Mike Leake (10-10, 4.10 ERA) will make his 31st start Tuesday. Leake gave up five runs in 6.1 inning in his last start at Houston, but allowed only one run over 13 innings in his two starts prior to that outing.