ST. LOUIS -- On Monday night, the Miami Marlins will have half of the National League's representatives in the All-Star Home Run Derby in their ballpark.

Giancarlo Stanton and Justin Bour got an early start on the competition Wednesday night, combining forces with teammate Marcell Ozuna to slug more than 1,600 feet of long balls.

Stanton's two got Miami off to a quick 6-0 lead, then Ozuna and Bour added solo shots that provided cushion in a 9-6 win over the St. Louis Cardinals at Busch Stadium.

Stanton and Ozuna each have 23 homers, and Bour has 19. Stanton and Ozuna are the first Marlins teammates to reach 20 before the All-Star break since Hanley Ramirez and Dan Uggla each clouted 23 in 2008.

"For me, it's fun," Ozuna said of matching Stanton. "He has more power than me, for sure. He can hit seven homers in a week. But it feels good to be up there with him."

It took Stanton all of five pitches to set the tone Wednesday. He lined a 407-foot 1-iron off the back wall of the Miami bullpen in left-center, off Mike Leake. An inning later, Stanton drilled a 3-0 pitch 415 feet to the seats in left-center, capping a five-run rally.

Miami did derive plenty of help in the second inning. Second baseman Matt Carpenter and first baseman Luke Voit lost one-on-one battles with bouncers hit hard and right at them. The errors forced Leake to get five outs, and all of the inning's runs were unearned.

Ozuna, who lost the team's homer lead after Stanton's second blast, pulled even on the first pitch of the third inning. He ripped a 411-foot shot to left-center to make it 7-0, eliciting scattered boos from the crowd of 40,204.

"When you go up there with a good approach and doing the right things, it feels good," Bour said. "We have fun with this when we win; but, if we're hitting homers and we're losing, it's not fun at all."

The Marlins (38-45) crept dangerously close to no-fun zone as St. Louis (40-44) constructed a mid-game rally against ailing starter Edinson Volquez and the middle relievers.

The Cardinals scored three runs in the third, getting an RBI double from Tommy Pham and a two-strike, two-out RBI single from Stephen Piscotty. After Ozuna's two-out RBI double in the fourth knocked out Leake, St. Louis responded with a sacrifice fly from pinch-hitter Jedd Gyorko in its half of the inning.

Pham grounded a two-run double down the right-field line in the sixth, drawing St. Louis within 8-6 and getting the tying run to scoring position. But Piscotty bounced out to third, stranding two.

That was it for the Cardinals' offense. The front-line Miami relievers -- David Phelps, Kyle Barraclough and AJ Ramos -- combined to retire nine of 10 men. Ramos pitched a 1-2-3 ninth for his 15th save in 16 chances.

Dustin McGowan (5-0) pitched 1 1/3 innings after the departure of Volquez because of a knee injury. Volquez lasted just four innings, giving up six hits and four runs, with two walks and a strikeout.

"His knee was barking on him," Marlins manager Don Mattingly said. "It's something that I guess he's had in the past."

Leake (6-7) left after a season-low 3 2/3 innings, yielding nine hits and eight runs, only three of them earned. He walked one and fanned two.

"Leake didn't have his best stuff, but he pitched well enough to let us win," Pham said. "That's all you can ask from your pitcher. We have to do a better job of going out there and just playing great, mistake-free baseball."

NOTES: St. Louis 3B Jedd Gyorko (left groin strain) missed his second straight start Wednesday night, with Greg Garcia again taking his place. Gyorko could return for the series finale with Miami on Thursday. ... Cardinals CF Dexter Fowler (right heel spur) went through pregame drills while wearing his cleats, an important step as he tries to return to the lineup. Fowler hadn't been able to work out in his cleats before Wednesday due to intense pain when he tried to wear them. ... Miami still hasn't decided on a starting pitcher for Saturday night's game in San Francisco. The spot is vacant after LHP Jeff Locke was designated for assignment Tuesday.