Grossman connected on solo drives in the first and fifth innings against right-hander Justin Dunn (3-1).

Tommy La Stella tripled to begin the sixth in Game 1, but the A’s couldn’t capitalize against former Oakland right-hander Kendall Graveman (1-3).

“That was great to be able to go out in a high-leverage situation, especially this whole month, and to be able to do that with some added Adrenalin,” Graveman said.

Khris Davis hit a sacrifice fly in the fourth inning, but that was it for the A’s, whose hitting is hardly where they would hope.

“I have no doubt in this team. We’re the best team in the division, I would take us over anyone,” Grossman said. “It’s been a grind.”

The typically slugging A’s (35-23), who will host a best-of-three wild-card series starting Tuesday at the Coliseum, are still struggling as an offense but doing just enough. They won 3-1 in 10 innings Friday night on Mark Canha’s two-run homer.

Liam Hendriks (3-1) pitched a perfect seventh before finding trouble in the eighth, when Ty France also singled home an insurance run for Seattle. France doubled in a run in the second game.

“Heck of a comeback,” Mariners manager Scott Servais said. “I can’t say enough about the effort and the grind. We have some grit.”