OAKLAND, Calif. -- Coco Crisp altered his batting approach and tried to muscle up in his last at-bat.
It couldn't have worked out any better for the Athletics' leadoff hitter.
"I was just going up there to swing as hard as I could," said Crisp of his sixth career game-ending hit. "Probably nine times out of 10 I ended up with a strike out with that approach. Tonight was that one time that it ended up working out. I'm not going to have that as my every day approach but I'm just grateful that it worked out tonight."
Crisp, who scored the tying run with two outs in the eighth inning on Yoenis Cespedes' triple, hit a towering home run off Seattle reliever Hector Noesi (0-1) on an 0-1 pitch. The ball landed just above the out-of-town scoreboard in right field.
Umpires met briefly to review the play before confirming Oakland's victory.
It was a welcomed victory for the A's after dropping two of three to Cleveland in their season-opening series after closer Jim Johnson had two late meltdowns.
Johnson wasn't available against the Mariners but four other Oakland relievers combined for six shutout innings to preserve the victory. Drew Pomeranz (1-0), the fifth A's pitcher, worked one scoreless inning for the victory.
"We played a day-nighter [Wednesday] and it felt like almost a doubleheader today," A's manager Bob Melvin said. "It was nice to squeak that one out, especially the way the game was going early on."
Cespedes and Sam Fuld also drove in runs for Oakland, which rallied from two runs down for its first walk-off victory of the season.
Abraham Almonte had two hits and an RBI for Seattle. The Mariners were coming off a series sweep of Anaheim and were attempting to go 4-0 for the first time since 1985.
After scoring 28 runs in the three games against the Angels, Seattle's offense managed just six hits against Oakland and stranded seven base runners.
"We played well (and) we pitched well," Mariners catcher Mike Zunino. "We did everything. We don't want to lose that way but we did some great things."
The Mariners scored in the first without the benefit of a hit.
Almonte hit a grounder that went through the legs of Oakland infielder Alberto Callaspo, who was making his first career start at first base. Second baseman Nick Punto chased down the ball in right field but threw wildly back to the bag for another error, allowing Almonte to take second.
Two batters later, Cano's groundout scored Almonte.
That put Seattle starter Roenis Elias in shape to become the first Cuban-born pitcher to win a game for Seattle before the Mariners' bullpen gave up the lead.
Elias, an all-star in the minors a year ago, allowed one runs and two hits in five effective innings but left with a no-decision. The 25-year-old lefty allowed only two runners past first base and struck out three and walked three.
The Seattle rookie didn't give up a hit until Nick Punto's sharp single to left with two outs in the fifth. Fuld followed with a triple after Seattle center fielder Almonte dived for the ball and missed.
Fuld tried to score on the same play but was thrown out at the plate on a relay from Cano. The play was reviewed and upheld.
Oakland failed to score after loading the bases with two outs in the seventh before Cespedes tripled in Crisp to tie it with two outs in the eighth.
Crisp's first home run of the season ended the game after more than four hours.
"You could tell his first swing that he was looking for something that he could pull and get up in the air," Melvin said. "That was his intent, and that's tough to do, going up there trying to hit a home run especially when you're a leadoff-type guy."
Chavez, making his first start since 2012, allowed two runs and five hits over six innings.
Melvin met with Johnson to check on the A's new closer after he took the loss in each of his first two appearances. "Everything gets real magnified when you're in the closer's role because when you have a bad day the team loses," Melvin said. "That's just the way it is." ... The A's voided the March 29 option of IF Jake Elmore and placed him on the 15-day disabled list because of a strained left quad. ... OF Michael Taylor cleared waivers and was sent outright to Triple-A Sacramento by the A's. IF Hiro Nakajima was also sent outright to Sacramento. ... RHP Dan Strailey faces Seattle RHP Chris Young on Friday. Young last pitched in the big leagues in Sept. 29, 2012. ... Mariners RHP Stephen Pryor (surgery) began a rehab assignment with Double-A Jackson on Thursday. ... RHP Taijuan Walker (shoulder) will make a rehab start for Single-A High Desert on Friday.