SAN FRANCISCO -- Madison Bumgarner is tough to beat under any circumstances. But the San Francisco Giants ace left-hander had been impossible to beat on his double-digit strikeout nights.

Until Saturday night, that is.

Center fielder Marcell Ozuna ignited a three-run fourth inning against Bumgarner with his second home run of the season, helping the Miami Marlins to a 6-2 victory.

Right-hander David Phelps remained undefeated this season with six innings of one-run ball as the Marlins evened their record at 3-3 on their 10-game trip.

Phelps outpitched Bumgarner (3-2), who lost for the first time in his career when recording 10 or more strikeouts. He fanned a season-best 10 in five innings, posting the 20th double-digit strikeout game of his career.

The Giants had been 19-0 and Bumgarner 17-0 when the left-hander struck out 10 or more in a game.

"He had good stuff. The strikeouts show it," Giants manager Bruce Bochy assessed of Bumgarner, who hadn't lost since April 11. "Sometimes you tip your cap to the other team."

With wins Thursday and Saturday in the four-game series, the Marlins assured themselves of another nonlosing trip to San Francisco. Miami has not lost a series at AT&T Park since 2009, going 15-6 during that stretch.

Two three-run uprisings, one against Bumgarner and the other against the San Francisco bullpen, lifted the Marlins to the win.

The reigning World Series Most Valuable Player had shut out the Marlins on two hits for three innings before Ozuna hit his second pitch of the fourth into the center-field bleachers for a solo homer to open the game's scoring.

"He's one of the best pitchers in the league," Ozuna noted of Bumgarner. "I just try to put the ball in play and the home run came."

The homer was the first of three extra-base hits the Marlins would get in the inning. Second baseman Jeff Baker and shortstop Adeiny Hechavarria added RBI doubles later in the inning, making it a three-run uprising that produced a 3-0 lead.

"He's got nasty stuff," Phelps said of his counterpart. "I commend our guys for getting his pitch count up early. Ozone (Ozuna) had the big swing."

Bumgarner left for a pinch hitter in the bottom of the fifth, having thrown 99 pitches. He allowed three runs, five hits and two walks. Ten of his 15 outs were by strikeout.

"Three runs in five innings, that's not that bad," Bochy said. "We had chances, but we couldn't keep the line moving. We couldn't put a crooked number up (on the scoreboard). They had two of them and that's what beat us."

Ozuna's home run was his second of the season. He also was involved in a key sequence when the Marlins tacked on three insurance runs off Giants reliever Jean Machi in the eighth inning.

After right fielder Giancarlo Stanton, who had struck out three times against Bumgarner, led off the eighth with a walk, Ozuna hit a sharp comebacker that deflected off Machi's arm.

Machi recovered the ball quickly and had plenty of time to get an out at first or second but threw to second baseman Joe Panik at second instead of shortstop Brandon Crawford, who was covering the base. Stanton was ruled safe on the play.

After a sacrifice bunt, reserve second baseman Donovan Solano grounded a two-run double down the right-field line, advancing the Miami lead to 5-1.

Hechavarria's two-out infield single, a play overturned in the Marlins' favor on video review, scored Solano and made it a three-run inning and a 6-1 game.

"If you can get guys to step up when others go down, that's how you win games," assured Phelps, referring to Solano, who had replaced an injured Baker (strained right oblique) in the fourth inning. "It's what good teams have to do."

Hechavarria had two hits and two RBIs for the Marlins. Third baseman Martin Prado also collected two hits, including one of Miami's four doubles, in its eight-hit attack.

Phelps (2-0) scattered six hits in his six innings. He walked one and struck out three.

Crawford and center fielder Angel Pagan had two hits apiece for the Giants, who haven't won a game in which their opponent scored since last Saturday. That stretch now includes four shutout wins and three losses.

NOTES: Marlins 2B Dee Gordon, who leads the majors in hits and batting average, did not play for a second straight day. While a sore right leg kept him on the bench Friday, his absence Saturday had more to do with the opposing pitcher, Giants LHP Madison Bumgarner, against whom Gordon had gone just 3-for-13 (.231). ... Giants 1B Brandon Belt went 0-for-3, ending at six his streak of games with at least one double. The franchise record is seven. ... Giants pitchers combined for 15 strikeouts. San Francisco hadn't lost a game when recording 15 or more strikeouts since 2010. ... The Marlins have won only five times in their history when striking out 15 or more times in a game. ... San Francisco manager Bruce Bochy said he will join a Giants contingent that will present 3B Pablo Sandoval his World Series championship ring Monday. The presentation will take place at a San Francisco downtown hotel, where Sandoval's new team, the Boston Red Sox, is staying during its series against the Oakland Athletics. ... Giants RHP Jake Peavy (strained back) will begin an extended spring training stint in Scottsdale, Ariz., on Monday. Peavy is hopeful of returning to the rotation in June.