PHOENIX -- Welington Castillo's home runs have come in bunches, and his latest Saturday enabled Arizona to avoid a season-long seven-game losing streak.

Castillo's three-run homer with one out in the eighth inning off Hunter Strickland lifted the Diamondbacks to a 6-5 victory over the San Francisco Giants at Chase Field, putting the final touches on a four-run comeback.

"I wasn't thinking about hitting a homer, because his sinker is really good, so I was trying to stay short and put the ball in play," said Castillo, who has homered in his last two games.

Castillo has 10 homers this season, four against the Giants. He hit seven in his first 21 games and then went 28 games without one before connecting again June 17.

"I know I went through a tough moment," Castillo said. "I don't worry about my hitting. I know I can hit a little bit. Just time, and it's going to come."

Brandon Crawford and Mac Williamson homered for the Giants (51-32).

Crawford and Williamson homered on consecutive pitchers in the fourth inning to give the Giants a 5-1 lead before Arizona rebounded to beat the Giants for the first time in six meetings at Chase Field this season.

Lamb and Chris Herrmann had two hits including a double for the Diamondbacks (37-46).

"It's a good win," Paul Goldschmidt said. "We know how far we are back from San Francisco, and even in the wild card. Any win is going to be big."

Michael Bourn doubled off Giants starter Jeff Samardzija to open the eighth inning before left-hander Josh Osich entered and walked the only batter he faced, Jake Lamb.

Castillo hit a 2-1 pitch from Strickland (3-1) in the left-center field seats for a 6-5 lead. It was his second homer in as many nights at Chase Field after not hitting one at home since April 24.

"I tried to throw a two-seamer (sinking fastball), left it over the plate and it didn't move," Strickland said. "I would say he got the best of it."

Right-hander Jake Barrett (1-0) pitched a scoreless eighth for his first career victory and Brad Ziegler pitched around a leadoff single in the ninth for his 17th save.

"That is one we let get away," San Francisco manager Bruce Bochy said.

Samardzija gave up four runs on eight hits in 7 1/3 innings. He struck out five and did not walk a batter.

Arizona starter Patrick Corbin gave up five hits and five runs (two earned) in 5 1/3 innings. He struck out five and walked three.

The Giants jumped ahead with three unearned runs off Corbin in the second. Buster Posey walked and took third on Crawford's single before shortstop Jean Segura threw wildly to home on Williamson's grounder to allow Posey to score.

Ruben Tejada singled in the second run, and the third scored when Segura could not field Samardzija's double play ball cleanly and Arizona had to settle for a force out at second.

Corbin doubled and Segura singled with one out in the third, and Corbin scored when Michael Bourn beat out a potential double-play grounder to shortstop. Corbin leads National League pitchers with 12 hits.

Crawford and Williamson homered on back-to-back pitches to open the fourth inning for a 5-1 lead. Williamson's homer hit the video board in center field, an estimated 460 feet.

Arizona make it 5-3 in the fourth inning when Lamb singled and Castillo and Herrmann followed with run-scoring doubles.

Arizona manager Chip Hale was ejected for arguing balls and strikes after the last of the sixth inning.

NOTES: San Francisco RF Hunter Pence (right hamstring strain) took batting practice before the game for the first time since going on the disabled June 2. Pence is expected to miss 6-to-8 weeks. "He's on target," manager Bruce Bochy said. ... San Francisco RHP Sergio Romo (flexor strain) is expected to rejoin the team Monday when it begins a six-game homestand against Colorado and Arizona, Bochy said. Romo has been out since mid-April. ... Arizona SS Nick Ahmed was placed on paternity leave after his wife delivered their first child Saturday night. Ahmed is expected to return Monday. RHP Enrique Burgos was recalled to fill the open roster spot. LF Rickie Weeks Jr. is expected to return from bereavement leave on Sunday, at which point the Diamondbacks must make another move. They played Saturday with 11 position players and 14 pitchers. ... Arizona 3B Jake Lamb is attempting to become the fourth player (five occurrences) in franchise history to have 20 doubles and 20 homers before the All-Star break. Lamb has 19 doubles and 18 homers. Paul Goldschmidt (twice), Matt Williams and Jay Bell have done it.