SAN FRANCISCO -- Hours before the Giants faced off against the D-backs on Tuesday night, Mike Yastrzemski was out on the field at Oracle Park, putting in extra work with hitting coaches Donnie Ecker and Dustin Lind to try to regain the rhythm at the plate that had been disrupted by a pair of trips to the injured list this season.

It didn’t take long for Yastrzemski to reap the fruits of that labor.

Yastrzemski's first career grand slam with two outs in the eighth inning capped an improbable comeback for the Giants, who erased a seven-run deficit to rally for a wild 9-8 win over the reeling D-backs on Tuesday night at Oracle Park.

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The Giants trailed, 7-0, in the top of the second inning after opener Zack Littell and bulk pitcher Sammy Long struggled in their second joint appearance of the season. But San Francisco clawed its way back into the game with a three-run second inning, highlighted by a two-run home run from Steven Duggar, and two runs in the sixth, pulling within three before staging the winning rally.

Brandon Belt led off the eighth with a double, then Donovan Solano singled. With two outs, pinch-hitter Curt Casali walked to load the bases for Yastrzemski, who entered Tuesday batting .224 in his first 49 games this year. Still, Yastrzemski promptly hammered a 1-2 changeup from D-backs reliever Humberto Castellanos into McCovey Cove to give the Giants a 9-8 lead, causing the 9,867 fans in attendance to erupt in thunderous roars.

It was the fourth career splash hit for Yastrzemski, who said he probably hadn’t hit a grand slam since playing in the wooden-bat Cape Cod League as a college player last decade.

“That was definitely the best grand slam I’ve ever hit, for sure,” Yastrzemski said.

Yastrzemski watched the shot rocket off his bat to make sure that the ball didn’t hook foul, before beginning his trot around the bases, which was a bit of a cathartic experience after his uneven start to the year. The 30-year-old slugger finished eighth in National League MVP Award voting after emerging as the Giants’ best player in 2020, but he hadn’t looked fully like himself after being hampered by oblique and thumb injuries this year.

“I was really fired up that I kind of squared a ball up and stayed through one,” Yastrzemski said. “I’d been a little off lately. It was tough coming back from a couple of injuries and trying to get my timing back and seeing the ball right. At that point, I was almost so frustrated with myself that I just kind of let it all go and just trusted what I’d been training, what my abilities were. I finally stuck to my game plan at the plate instead of chasing or getting outside of myself.”

Yastrzemski credited the work he did with the Giants’ hitting coaches before the game with helping him to train for that moment against Castellanos in the eighth.

“We were working on my path all day and really trying to keep everything moving toward the middle of the field,” Yastrzemki said. “That was kind of the exact swing that we worked on there. I got a pitch that was middle-in and didn’t try to do too much with it. I didn’t try to yank it, just tried to stay through it and put a good swing on it.”

Closer Tyler Rogers retired Carson Kelly, Christian Walker and Asdrúbal Cabrera in order in the ninth to seal the dramatic win for the Giants, who improved to a National League-best 42-25. The D-backs, meanwhile, have lost 12 games in a row and dropped 21 straight on the road dating back to April 25, when former San Francisco ace Madison Bumgarner tossed a seven-inning no-hitter at Atlanta.

“I don’t feel like we ever felt out of that game,” San Francisco manager Gabe Kapler said. “We could see multiple paths to getting back into it and winning it, even after the rough first few innings and how everything started. I think there’s a lot of pride from the players for just grinding through that game and giving Yaz a chance to get that big hit.”

It was the Giants’ largest comeback victory since they overcame an eight-run deficit in a 12-11, 11-inning win over the Reds on May 3, 2019, in Cincinnati.

“It was pretty awesome,” said Belt, who went 3-for-3 with a double and a triple. “I think the thing that was most fun about today was it was really a full team effort. It took every single one of us to go out there and grind our butts off to come out with this victory.”