PHILADELPHIA -- With the bases loaded in the third inning and the Philadelphia Phillies trailing by two runs, Maikel Franco swung and missed so hard his helmet flew off his head and rolled a few feet away.

"I think that happened 20 or 25 times last season," Franco said.

The Phillies third baseman collected himself and on the next pitch drove a fastball by Wei-Yin Chen into the center-field seats for his second grand slam in two weeks, leading the Phillies to a 7-4 win over the Miami Marlins on Wednesday night at Citizens Bank Park.

"After two breaking balls, I was ready for the fastball," Franco said. "I just needed to calm down and just put good contact on it."

Vincent Velasquez pitched a season-high 6 1/3 innings to pick up his first win of the season and Freddy Galvis and Michael Saunders each hit home runs as the Phillies won their fifth straight game.

Philadelphia (10-9) moved above .500 for the first time since opening the season with a win in Cincinnati on April 3.

Velasquez enjoyed his best outing, allowing three runs and six hits and throwing 68 of his 97 pitches for strikes in front of the crowd of 26,191.

It was just the fourth time in 28 starts that Velasquez pitched into the seventh inning. A big reason, Phillies manager Pete Mackanin said, was Velasquez's 19 first-pitch strikes against 26 batters.

"Even though he's not striking people out like we know he can and will, he was using all his pitches and he got us into that seventh inning, which was huge," Mackanin said. "He's not trying to strike everyone out with perfect pitches. He pitched to more contact, which is good."

Velasquez agreed.

"Every outing I've done something a little better," he said. "If I'm going to go deep in games, I've got to get ahead (of the count) as soon as possible. Whether it be changeup, curveball or slider, I've got to attack."

Chen (2-1) took the loss for the Marlins (10-9), who received a solo home run by Martin Prado, two RBIs by Adeiny Hechavarria and an RBI groundout by Christian Yelich.

Miami saw its two-game win streak snapped.

"I tried to keep us in it," Chen said through a translator. "I had six days' rest because of (Tuesday's) rainout. As a player, you need to deal with this kind of situation. Unfortunately, I didn't do well and I wasn't able to help the team."

The Phillies received 2 2/3 innings of strong relief from Joely Rodriguez, Joaquin Benoit and closer Hector Neris, who allowed a ninth-inning run in a non-save situation.

After allowing no hits in seven innings in his previous start on April 18 in Seattle, Chen surrendered four runs and seven hits in five innings against the Phillies, the big blow coming on Franco's third-inning blast.

Franco also had two singles.

"He missed a spot there," Marlins manager Don Mattingly said of Chen's fastball to Franco. "Otherwise, he was not bad. You like to stay away from those because they're quick runs and they change games.

"When you leave balls out over the plate for guys who like balls out over the plate, you're going to get hurt."

Having scored 13 runs in their previous two games, both wins, the Marlins grabbed an early 1-0 lead when Dee Gordon led off with a triple to right field and scored on Yelich's RBI groundout. It was Gordon's 11th run scored in 19 games, second most on the team behind Yelich.

The Marlins tacked on a run to take a 2-0 lead in the third on a home run by Prado, who drove an 0-1 pitch from Velasquez into the seats in left field for his second homer in just six games this season.

Prado missed the start of the season with a calf injury.

It was the Marlins' 25th home run in 19 games.

Chen, meanwhile, had picked up where he left off in his last outing. Chen retired six of the first eight batters he faced but opened the third inning by allowing a single to Velasquez, his second hit of the season.

Velasquez moved to second on Aaron Altherr's single and was held up at third base on Odubel Herrera's single to center field. It was a prudent move by Phillies third base coach Juan Samuel because it loaded the bases with one out for Franco.

The third baseman worked the count to 2-2 and drove Chen's next pitch into the seats in center field, just above the 387-foot sign, giving Philadelphia a 4-2 lead. It was Franco's fourth home run of the season, his third career grand slam and his second slam in as many weeks. He also hit a grand slam against the New York Mets on April 12 in a 5-4 home loss.

The Phillies and Marlins close out the series on Thursday afternoon when Philadelphia right-hander Jeremy Hellickson (3-0) faces Miami right-hander Edinson Volquez (0-2).

NOTES: Phillies RHP Clay Buchholz, 32, is not ruling out a return to the lineup in September after having surgery last week to repair a torn flexor tendon in his right arm. Buchholz is scheduled to become a free agent after the season. ... Phillies LF Aaron Altherr made his sixth straight start in place of Howie Kendrick, who is sidelined due to an oblique injury. ... Marlins LHP prospect Dillon Peters was placed on a "no-throw" status following surgery to repair multiple fractures in his left thumb. Peters, 24, fractured his thumb on a comebacker while pitching for Double-A Jacksonville on April 17. One of the Marlins' top prospects, he underwent surgery on Friday and is expected to begin throwing in six to eight weeks. ... The Marlins are on the third leg of a three-city, cross-country road trip that began with stops in Seattle and San Diego. Since leaving Miami on April 6, the Marlins have traveled 6,145 miles, with a return flight to Miami scheduled for Thursday night, increasing the total mileage to 7,162.