Juan Soto gave the Padres a quick lead with a solo homer in the first. Xander Bogaerts and Gary Sanchez hit solo homers in the second, and Garrett Cooper delivered a three-run shot in the sixth. The home runs accounted for four of the Padres' six hits.
Meanwhile, Snell (12-9) lowered his majors-leading earned run average to 2.50. He gave up three hits and four walks with eight strikeouts. He is third in the majors with 201 strikeouts.
Harrison (1-1) was making his third start with the Giants. He gave up six runs on six hits and two walks with five strikeouts in 5 2/3 innings and saw his ERA jump to 2.50 from 1.86 ERA.
All four of San Diego's homers traveled at least 400 feet.
With two out in the first, Soto drove a 95 mph fastball 415 feet to center for his 27th homer of the season.
Bogaerts led off the second with his 16th homer, a 402-foot drive to center off a 2-and-1 breaking ball. It was Bogaerts' third homer in his last seven games at Petco Park. Two hitters later, Sanchez hit his 19th homer of the season — a 430-foot drive to center off a 1-and-1 changeup.
Fernando Tatis Jr. led off the Padres' sixth with a single but was forced at second Soto's ground ball. Bogaerts drew a two-out walk and Cooper, whom the Padres acquired from Miami at the trade deadline, hit a 400-foot bomb to left-center. It was his 15th homer of the season.
The Giants broke up the shutout in the ninth. Left-handed reliever Ray Kerr walked Casey Schmitt, hit Wade Meckler with a pitch allowed Austin Slater's double to right field to score Schmitt. Kerr then got a strikeout and groundout to end the game.
—Field Level Media