PHOENIX — Michael Conforto and Brett Wisely each hit three-run homers in San Francisco’s six-run third inning, and the Giants won their fifth straight against playoff contenders by crushing the Arizona Diamondbacks 11-0 on Tuesday night.

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The Giants have nearly perfected the role of spoiler recently, going 7-1 against Baltimore, Kansas City and Arizona. San Francisco stretched its season-high winning streak by bashing five homers against the Diamondbacks, including three off Brandon Pfaadt (10-10) in the first three innings.

“Things happen like this and it gets contagious,” Giants manager Bob Melvin said. “You start playing well and you just feel like you’ve got a chance to win.”

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Up Next

Giants RHP Mason Black (1-4, 5.88 ERA) faces Diamondbacks RHP Zac Gallen (13-6, 3.74) in the series finale on Wednesday.

Giants’ Offense Explodes in Third Inning

Patrick Bailey hit a solo homer in the second inning, Conforto launched his 20th in the third and Wisely followed with his three-run homer to put the Giants up 7-0.

Tyler Fitzgerald hit a two-run homer and Heliot Ramos added a solo shot among his four hits. Logan Webb (13-10) allowed four hits in six scoreless innings.

“We’re having fun and that’s a good thing to watch from the dugout,” said Webb, the first Giants pitcher with consecutive 200-inning seasons since Jeff Samardzija in 2016-17. “We’re making plays, we’re pitching well and that’s building chemistry.”

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Diamondbacks Struggle at Crucial Time

The Diamondbacks are laboring at the wrong time.

Arizona blew an 8-0 lead in a loss to Milwaukee, opened this series with a 6-3 loss and had six hits Tuesday night. The Diamondbacks’ lead over Atlanta, a 5-1 winner over the New York Mets, dropped to a half-game for the final NL playoff spot with four games remaining.

“Usually I try to filter things and come up with something that’s positive, but I don’t think there was much positive that came from this game today,” Diamondbacks manager Torey Lovullo said. “We’ve got to play better baseball.”

Pfaadt bounced back from an ugly start — eight runs in 1 2/3 innings — by striking out 12 in a win over Milwaukee his last start.

The right-hander followed with another shaky outing.

Pfaadt gave up Bailey’s eighth homer of the season in the second inning and got some help later in the inning from right fielder Corbin Carroll, who reached over the wall to steal a three-run homer from Mike Yastrzemski.

No one had a chance on Conforto’s shot in the third, a three-run blast off the overhang in left-center. Wisely followed a fielding error by Arizona shortstop Geraldo Perdomo with his three-run shot off Blake Walston.

Pfaadt allowed five runs — four earned — on six hits in 2 2/3 innings.

“I felt great physically, felt like we made some good pitches early,” Pfaadt said. “We just left some fastballs in the middle and paid the price for it.”

Injury Updates and Next Game

Diamondbacks: C Gabriel Moreno went 0 for 3 after missing Monday’s game with an oblique strain. … RHP Ryne Nelson is expected to come off the injured list soon after missing two weeks with shoulder inflammation.