SEATTLE — Robinson Cano’s three-run, eighth-inning home run completed Seattle’s comeback from a four-run deficit as the Mariners rallied to beat the Boston Red Sox 5-4 Tuesday night.

With one out, Cano hit a 1-2 pitch from new Boston reliever Fernando Abad into the right field seats.

Red Sox starter David Price dominated the Mariners for seven scoreless innings before losing his grip in the eighth. He gave up four consecutive hits to open the inning before the Red Sox turned to their bullpen.

Four of Seattle’s five runs in the eighth were charged to Price, who allowed seven hits over seven-plus innings and did not factor into the decision.

Abad, who was acquired in a deadline trade with the Minnesota Twins on Sunday, made his Red Sox debut and gave up a three-run homer to the first batter he faced. Abad (1-5) was added to the roster after Monday night’s win.

Mike Zunino led off the eighth with a home run, pulling Seattle (53-52) within 4-1. Guillermo Heredia added an RBI single, his first major league hit, as Boston’s lead shrunk to 4-2 before Cano’s 24th home run of the season completed the comeback.

Mariners rookie reliever Edwin Diaz, promoted to the closer’s job after veteran Steve Cishek struggled in back-to-back games Sunday and Monday, made the most of his first opportunity. He struck out three of the four batters he faced in a scoreless ninth to earn his first career save.

Donn Roach (2-0) earned the win after giving up one run on one hit in two innings.

Mariners starter Wade LeBlanc allowed three runs on five hits over six innings and left the game with Seattle trailing 3-0.

Boston veteran David Ortiz went 1-for-3 with two RBIs. He gave the Red Sox a 1-0 lead with an RBI double in the first inning and added a sacrifice fly in the eighth, putting Boston ahead 4-0.

Hanley Ramirez had two hits for the Red Sox (58-47). Boston prospect Andrew Benintendi made his major league debut as a pinch hitter and wound up going 0-for-2. He struck out on a 99 mph Diaz fastball to end the game.

Ramirez’s 14th home run of the season helped the Red Sox build a 3-0 lead in the fourth inning. Ramirez crushed a 1-1 pitch from LeBlanc 454 feet into the stands in left-center field for a solo shot. Aaron Hill added an RBI single in the two-run fourth.

Ortiz, who has done plenty of damage at Safeco Field over the years, collected his 42nd career RBI at the stadium with a first-inning double. Ortiz’s two-out hit brought in Dustin Pedroia from first base, giving the Red Sox a 1-0 lead.