Mitch Haniger hit a grand slam and Emerson Hancock pitched six quality innings as the Seattle Mariners defeated the visiting Arizona Diamondbacks 6-1 Friday night in the opener of a three-game interleague series.

Josh Rojas and Mitch Garver added solo shots for the American League West-leading Mariners, who have won eight of their past 10 games.

Kevin Newman hit a solo homer for the Diamondbacks, who lost for the sixth time in nine games.

Arizona ace Zac Gallen (3-2) left in the sixth inning due to right hamstring tightness.

Gallen walked Rojas leading off the sixth, and after Julio Rodriguez fouled off a 1-1 fastball, Diamondbacks manager Torey Lovullo and a member of the team's training staff came out to the mound to check on Gallen. Lovullo signaled for Scott McGough to enter from the bullpen, and Gallen trudged to the dugout.

Gallen (3-2) was charged with three runs on three hits and one walk in five-plus innings. The right-hander walked one and struck out three throwing 64 pitches.

Rodriguez greeted McGough by grounding a single to right field, and Cal Raleigh walked to load the bases. Haniger then hit a 3-2 fastball that cleared the fence in deep left-center field to make it 6-1.

Rojas, acquired from Arizona at last year's trade deadline as part of the deal for closer Paul Sewald, homered leading off the bottom of the first inning. Rojas was filling the top spot in the order with J.P. Crawford on the injured list because of a strained right oblique.

Garver hit a towering blast just inside the left field foul pole with two outs in the second to put Seattle up 2-0.

Hancock (3-2), a rookie right-hander, allowed one run on two hits in six innings, with two walks and four strikeouts. He got the Diamondbacks to ground into double plays in three of the first four innings.

Arizona's Christian Walker led off the second inning by lining a single to center. The only other hit Hancock gave up was Newman's leadoff homer to left-center in the sixth.

The Diamondbacks loaded the bases in the ninth on an infield single and two walks before Cody Bolton got Eugenio Suarez to ground out to third to end the game.