PHOENIX -- San Francisco third baseman Casey McGehee hit a two-run home run and rookie right-hander Chris Heston picked up his first major league victory when the Giants beat the Arizona Diamondbacks, 5-2, at Chase Field on Tuesday.

Heston, recalled Tuesday to take injured Matt Cain's spot in the rotation, gave up three hits and two unearned runs in six innings. One Arizona run scored after an errant pickoff throw and the other on a passed ball.

McGehee, acquired to replace Pablo Sandoval, hit his first homer of the season in the ninth inning. He had a double Wednesday and had four hits in the series.

Left fielder Nori Aoki had three hits and drove in a run for the Giants (2-1), who have won nine straight series at Chase Field.

Shortstop Brandon Crawford and second Matt Duffy each had two hits and an RBI for the Giants.

Heston, 26, struck out five, walked two and pitched out of a bases-loaded situation in the fourth inning. His only previous major league start was a no-decision on the final day of the 2014 season.

Arizona first baseman Paul Goldschmidt singled and scored for the D-backs (1-2).

D-backs right-hander Jeremy Hellickson (0-1) made the first of his 109 career starts in the NL after being acquired from Tampa Bay in the offseason.

Right-hander Santiago Casilla pitched the ninth for his second save.

Center fielder A.J. Pollock was hit by a pitch to open the D-backs' first inning, took third on Heston's errant pickoff throw to first base and scored on second baseman Chris Owings' groundout for a 1-0 lead.

Aoki singled to drive in Crawford with two outs in the second inning, and Duffy followed with an RBI double to give the Giants a 2-1 lead.

The Giants went ahead 3-1 in fifth inning when McGehee led off with a double and scored on Crawford's one-out single, knocking out Hellickson. The right-hander gave up nine hits and three runs in 4 1/3 innings during his first National League start.

NOTES: Giants 1B Brandon Belt was diagnosed with a mild groin strain after an MRI was read Wednesday, and he is day-to-day, manager Bruce Bochy said. Belt was removed from Tuesday's game when he pulled up while chasing a foul pop behind first. ... Giants RHP Jake Peavy threw 45 pitches in a bullpen session Wednesday, and he might be read to start Sunday at San Diego, Bochy said. Peavy shagged balls in the outfield and was to take more treatment on his sore back before the game Wednesday. ... D-backs first-year manager Chip Hale's mother, Yvonne, was in the crowd when Hale got his first victory Tuesday night. "She is way more intense than me," Hale said. "My sister (Kathleen) was back in the Bay Area, pacing around the house like it was the World Series." Hale said the extent of his celebration was the postgame clubhouse beer shower: "I just went home and went to bed," he said. "That's too late for me these days."