Martinez went 4-for-5, scored three times, drove in five and was a triple shy of the cycle. His home run was No. 23 on the season, tying him with Mike Trout for the MLB lead.
"Good at-bats the whole day," said Red Sox manager Alex Cora. "The two doubles, he just missed the second one, and the home run, he hit a missile to center field and you saw what happened. This guy, he's that good. It's good that we had traffic in front of him. Everybody from top to bottom did an outstanding job staying in the game, just believing."
Thanks to the mashing of Martinez, the Red Sox were able to offset the monster performance by Cruz, who hammered two three-run homers off of knuckleballer Steven Wright as part of a 4-for-5, seven-RBI performance.
"He was off in the first inning, and he made some adjustments," Cora said. "It's one of those that he was getting close to getting back, and then [Cruz] happened. That's basically what happened."
But Martinez -- who is off to an MVP-caliber start to the season -- happened for the Red Sox.
"When we went down 10-5, I remember just thinking and talking in the outfield to the guys during the pitching change that we were down 10-5, but it didn't feel that way," said Martinez. "I felt we were really still in this game. And that's kind of how I felt the environment was in the dugout during the game today."
For the second straight day, the Sox established a season high in hits. The 20-hit onslaught came a day after Boston banged out 16 hits in a getaway-day win over the Twins.
"It's 162 games, and we're going to go through stretches like we did in Minnesota that we felt like we had no chance offensively, and then all of a sudden, this happened," said Cora.
This game was wild from the outset. The Red Sox rallied back from a deficit of 4-0 in the top of the first to take a 5-4 lead in the bottom of the first. And when they trailed 10-5, they again didn't flinch, scoring one in the fifth, three in the sixth and five in the seventh.
Martinez's two-run homer in the sixth came off a 1-2 fastball from Mariners reliever Nick Vincent to get the Red Sox back within striking distance at 10-8. Mitch Moreland followed with a triple, and Xander Bogaerts -- who later left the game with a left index finger sprain -- made it a one-run game with an RBI single.
In the seventh, Andrew Benintendi made it 10-10 with an RBI single. And it was Martinez who put Boston in front for good with his two-run single up the middle.
"It was a weird game," said Benintendi. "It was one of those, when you're down 10-5, there was a lot of game left. The way it was going, it was like, 'We're going to come back.' We just put good at-bats together, took our walks, and got those big hits."
Wright endured one of the worst starts of his career, surrendering four runs in the top of the first and a total of 10 earned runs over 3 1/3 innings. In one start, Wright's ERA went from 1.23 to 3.38.
Yet the Red Sox won anyway with a batting barrage against Wade LeBlanc and several Seattle relievers.
The game couldn't have played out any differently than last week's LeBlanc-Wright matchup at Safeco Field, which the Mariners won, 1-0.
"He pitched a great game against us last time," Martinez said. "It was one of those things where we all had a little chip on our shoulder coming into today. We were just like, 'Let's go. Let's get this guy.' I think everyone was just a little more focused."
MOMENTS THAT MATTERED Martinez's first strike: Down 4-0 early, the Red Sox struck back quickly against LeBlanc in the bottom of the first, and the hit that seemed to change the momentum was Martinez's RBI double to left that brought home Mookie Betts to make it a three-run game with nobody out.
"Yeah, I mean I just think bouncing back the way we did in that first inning was probably the biggest thing," said Moreland. "Coming back out and scoring some runs and getting back into the ballgame there was a big one for us."
SOUND SMART This marked the first time the Red Sox won a game in which their starter allowed 10-plus runs since May 8, 1946, when Mickey Harris allowed 10 runs (seven earned) against the White Sox.
HE SAID IT "To get down by a pretty good many early and battle back, take the lead, lose it again, get down big again, and then come back and win, that's some fight. We've got a great group in here. You know, that was a good one for us." -- Moreland
UP NEXT Left-hander Eduardo Rodriguez (9-1, 3.59 ERA), who has won his last six starts, will try to stay hot when he takes the mound in Saturday's middle game of this three-game series. Rodriguez beat the Mariners last time out with a strong start, as he gave up two runs over six innings while striking out nine. The Red Sox are 13-1 in his starts this season. Seattle counters with righty Mike Leake (7-4, 4.47). First pitch is scheduled for 7:15 p.m. ET.