SAN FRANCISCO -- All-Star or not, Pablo Sandoval is having the time of his life.

Sandoval boosted his bid to be named the final NL All-Star by hitting his first career grand slam and helped Matt Cain earn his 10th victory, and the San Francisco Giants withstood a late rally to beat the Florida Marlins 5-4 on Monday night.

Sandoval delivered on the night the Giants began their "Vote Pablo" campaign for the All-Star Game -- complete with stickers, signs, advertising behind home plate and onsite computers for fan voting. Sandoval is one of five players vying for the final National League spot, to be chosen by the fans. He hopes to join Cain (10-2) and reigning NL Cy Young Award winner Tim Lincecum at the Midsummer Classic next week in St. Louis.

"There's big support for me, from the fans and my teammates," Sandoval said. "It's one of the biggest moments for me. It's fun."

"Yeah, I'll go online," manager Bruce Bochy quipped about casting his vote.

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Many of the 26,995 fans chanted "Let's Go Pablo!" when he stepped in to bat against Sean West (3-3) in the fifth inning. Sandoval clobbered a 1-0 pitch deep into the left-field seats, pumping his fist as he neared the end of his trot. He came back out of the dugout for a curtain call -- also his first -- and the crowd roared again when he ran out to his spot at third base in the top of the sixth.

It was Sandoval's 13th homer this year and second grand slam of the season for San Francisco. Edgar Renteria had the other on April 21 against San Diego.

"He's definitely making his case, even though he shouldn't have to make his case," closer Brian Wilson said. "Unfortunately, I couldn't vote a million times."

Nate Schierholtz added a sacrifice fly as the Giants won for the sixth time in nine games.

Cody Ross' ground-rule double in the second was Cain's only baserunner in scoring position until Chris Coghlan reached on Renteria's fielding error at shortstop in the fifth and advanced on Emilio Bonifacio's double. Coghlan later scored on a wild pitch, then Jorge Cantu singled in Florida's second run.

A 13-game winner during his standout rookie campaign in 2006, Cain ended a three-start winless stretch and has his second-most victories during five years in the majors. He struck out five and walked two in 6 2/3 innings, allowed one earned run and five hits. Wilson allowed two runs in the ninth and missed a routine double-play ball with the bases loaded that allowed one of the runs to score, throwing to second rather than home. He survived for his 22nd save in 26 chances, retiring Bonifacio with the winning run on first on his 37th pitch.

"I had it in my mind already. Yeah, I should have gone home," Wilson said. "I didn't. We've all had those. Not everybody has them in the ninth."

West loaded the bases in the fifth after consecutive one-out walks to Cain and Aaron Rowand. Sandoval came up big two batters later.

Cain has been the hard-luck guy in recent years lacking run support, so he sure enjoyed seeing Sandoval's power stroke.

"I don't know how you could ask for anything better than that," he said. "I don't know if anybody in the states is not going to know his name after tonight."

Marlins manager Fredi Gonzalez held shortstop Hanley Ramirez out of the starting lineup for the second straight day with a right hip flexor. Ramirez, who won All-Star fan voting to be the starting shortstop for the NL, was hurt rounding the bases Saturday against Pittsburgh.

The Marlins had won five of six, but couldn't produce enough timely hits as the club kicked off a seven-game road trip before the All-Star break.

"We had some life in the ninth, we had some good at-bats there," Gonzalez said. "Wilson was able to get the last out."

Notes

The Giants lost LHP Randy Johnson for at least two starts, placing the Big Unit on the 15-day DL with a strained throwing shoulder. ... Injured Marlins RHP Anibal Sanchez, sidelined with a sprained shoulder, threw a light bullpen session. ... San Francisco OF Randy Winn got the night off. ... Kevin Frandsen, called up from Triple-A Fresno to take Johnson's roster spot, came in as a defensive replacement in the seventh.