Ryon Healy and Mike Zunino also homered for the Mariners in the rubber match of the three-game series. Jean Segura had four hits and Andrew Romine added three hits for the Mariners to lead a 17-hit attack.

Russell Martin hit a two-run homer for Toronto and Josh Donaldson added three hits.

Mariners starter Mike Leake (4-3) allowed two runs, six hits, one walk and struck out six over seven innings for his second win in his last three outings.

Toronto starter J.A. Happ (4-3) allowed seven runs, 10 hits, two walks and struck out three in 3 1/3 innings to take his second straight loss.

Seager hit his fourth career grand slam in the first inning to put the Mariners ahead 4-0. It came after singles by Segura and Robinson Cano and a walk to Healy.

The Mariners built their lead to 5-0 in the second on Segura's double and Mitch Haniger's single.

The Blue Jays struck back in the bottom of the inning with Martin's fifth homer of the season, which followed Kevin Pillar's double.

Healy hit his sixth homer of the season in the third.

The Mariners scored again in the fourth when Andrew Romine, Segura and Haniger singled and Cano hit a sacrifice fly to left. Jake Petricka replaced Happ.

Seager led off the fifth against Petricka with his sixth homer of the season, giving him his seventh career multi-homer game.

Marc Rzepczynski replaced Leake for the eighth inning, allowing an infield single to Lourdes Gurriel Jr. and a walk to pinch hitter Anthony Alford. Chasen Bradford took over and yielded a single to Donaldson to load the bases. James Pazos replaced Bradford and induced a double-play grounder by Yangervis Solarte with Gurriel scoring.

Zunino led off the ninth against Tim Mayza with his sixth homer of the season.

Edwin Diaz struck out the side in the ninth for Seattle.

--Field Level Media