SAN FRANCISCO -- Austin Slater’s reworked swing continues to yield impressive results for the Giants.

Slater delivered a pinch-hit grand slam to the opposite field to help power the Giants to an 8-4 win over the Cardinals on Saturday night at Oracle Park. It was the first career grand slam for Slater, who is now 6-for-11 with two home runs and nine RBIs in four games since being recalled from Triple-A Sacramento on Monday.

“Obviously, that’s the goal going into the at-bat,” Slater said. “Get something in the air and do some damage with it. It was a big spot in the game, too, which makes it even more special.”

With the game tied at 1 in the fourth inning, the Giants loaded the bases with some help from Cardinals left fielder Tyler O’Neill, who allowed a fly ball off the bat of Joe Panik to drop following a miscommunication with center fielder Dexter Fowler. The Giants followed by sending Slater to hit for reliever Sam Dyson, who entered the game in the third after starter Madison Bumgarner suffered a left elbow contusion on a first-inning comebacker.

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Slater drove a 1-0 slider from Cardinals right-hander Miles Mikolas to the top of the right-field wall, putting the Giants ahead, 5-1. The 26-year-old outfielder became the first Giant to hit a pinch-hit grand slam since Rich Aurilia on June 12, 2003, against the White Sox.

“If you get the ball up in the air in that area, it carries well,” manager Bruce Bochy said. “It’s short in that area. It carries pretty good, so Slater, when he hit it, I said, ‘That ball is out.’”

After hitting .251 with a .640 OPS in 74 games with the Giants last year, Slater spent the offseason working to tweak his swing at the front office’s request. The Giants wanted Slater to alter his bat path, as he finished the 2018 campaign with a 63.1 percent ground-ball rate, the highest in the Majors among hitters with a minimum of 200 plate appearances.

After consulting hitting guru Craig Wallenbrock, Slater worked to flatten his swing to stay in the strike zone longer and stay behind the ball. Slater wasn’t completely comfortable with the changes upon arriving at Spring Training, as he batted just .185 in 12 Cactus League games and was left off the club’s Opening Day roster, but he eventually settled into his new swing at Triple-A Sacramento.

At the time of his promotion, Slater was batting .308 with a .965 OPS and 12 home runs over 70 games. The sample size remains small, but so far, he’s showing that his new swing can play in the Majors, too.