In a dramatic 15-inning clash, Jorge Polanco delivered the winning run with a single to right field, sealing a 3-2 victory for the home team over the Detroit Tigers in the decisive game of the American League Division Series.
Luis Castillo, making his first relief appearance in the big leagues, pitched one and one-third innings to earn the win, sending his team to the ALCS for the initial occasion since 2001.
Seattle will now face the Blue Jays for the championship in a showdown between franchise counterparts. The series opener is scheduled for Sunday in Toronto.
Kerry Carpenter accounted for all of Detroit's offense with a home run in the sixth inning.
The Mariners evened the score at two runs apiece in the seventh on a substitute batter's run-scoring hit.
Each squad threatened repeatedly in extra innings, with the home team grounding into twin killings in both the later extra innings.
Tarik Skubal and George Kirby engaged in a low-scoring battle in the early innings.
The left-hander, a Cy Young Award favorite, allowed one run on a couple of hits with no walks and 13 strikeouts over six innings. He set a playoff mark with back-to-back K's.
His sole allowed score came in the early going, when a two-base hit, stolen base, and sacrifice fly brought home a point for the home side.
Kirby opened with five scoreless innings before surrendering a lead-off double in the middle inning. After a pitching change, the Tigers batter went deep on a pitch to give the visitors the advantage.
The starter lasted five-plus innings and was responsible for a single score on three hits with no walks and six strikeouts.
This victory signifies a major milestone for the Seattle franchise, who move forward to compete for a place in the championship after a long postseason absence.