Roy Oswalt gingerly bent down to put on his shoes and left the ballpark with a slight limp in his gait.

Oswalt hopes to make his next start. His back might not let him.

Pinch-hitter Greg Dobbs hit a go-ahead two-run single against his former team and the Florida Marlins rallied to beat the Philadelphia Phillies 4-3 Friday night.

It may have been a costly loss for the NL East-leading Phillies.

Oswalt pitched six impressive innings before getting hurt. He allowed two runs and four hits, striking out six. He didn't allow a hit until Logan Morrison led off the fifth with a home run into Philadelphia's bullpen.

"It's not to the point where it's unbearable," Oswalt said.

The team initially said Oswalt strained his lower back. But Oswalt said the pain was in the middle.

The three-time All-Star has been on the disabled list six times in his career, though he's made at least 30 starts eight straight seasons. A few of those trips to the DL were for lower back injuries.

"This is totally different," Oswalt said. "The others weren't good."

Oswalt plans to take the next two days off and then he hopes to throw on Monday. His next scheduled start is Wednesday against Milwaukee.

"It's a muscle spasm," Oswalt said.

Oswalt said he felt something in his back during the fifth inning. It tightened up even more when he ran to first after putting down a bunt in the bottom of the sixth. He stayed in and ran the bases, but came out after trying his warmup pitches.

"There was no sense leaving him in," manager Charlie Manuel said.

Five Marlins relievers combined for four scoreless innings after starter Javier Vazquez struggled through five. Edward Mujica (2-1) worked the sixth. Ryan Webb pitched a perfect seventh, Randy Choate snared a line drive against the only batter he faced and Clay Hensley got the two he faced out. Leo Nunez finished for his fifth save in as many tries.

Vazquez allowed three runs and five hits. He walked four and had to pitch out of the stretch most of the night with runners on base.

The Phillies' well-rested bullpen that hadn't been used the previous two games couldn't hold the lead after Oswalt departed.

J.C. Romero allowed an infield single to Morrison. Danys Baez (1-1) relieved and walked Gaby Sanchez. John Buck followed with a soft single to center to load the bases. After Donnie Murphy popped out to second, Dobbs lined a two-run single to left to put the Marlins ahead 4-3.

Dobbs spent the previous four seasons in Philadelphia. He batted .301 and was a key bench player for the World Series championship team in 2008.

The Phillies' bullpen was fresh because Roy Halladay and Cliff Lee pitched consecutive complete games. Lee tossed a 12-strikeout, three-hit shutout against Washington on Thursday. Halladay took a shutout into the ninth and went the distance in a 3-2 win a night earlier.

For a while, it seemed as if Oswalt would make it three in a row. Wearing short sleeves on a chilly night, Oswalt baffled hitters with a sharp fastball and deceptive offspeed pitches. He retired the first 11 batters before Hanley Ramirez walked in the fourth.

The Phillies jumped ahead with two runs in the first. Shane Victorino walked to start the inning and Jimmy Rollins lined a one-out double to right. Ryan Howard drove in the first run with a deep sacrifice fly. Raul Ibanez singled in Rollins to make it 2-0.

After Morrison's shot cut it to 2-1, the Phillies regained their two-run cushion in the bottom half. Victorino walked and Polanco singled. After Rollins flied out and Howard lined out, Ibanez hit an RBI single for a 3-1 lead.

But the Marlins answered in the sixth. Chris Coghlan and Omar Infante hit consecutive one-out doubles to get Florida within 3-2. Oswalt then retired Ramirez on a grounder to second and got Mike Stanton to foul out to leave the tying on third.

Stanton, the promising sophomore cleanup hitter, was no match for the veteran right-hander. Oswalt got him to swing and miss at a nasty 72 mph curve. He then busted him inside with a 92 mph fastball that Stanton popped up to catcher Carlos Ruiz.

A crowd of 45,667 on Jackie Robinson Night was the second-largest in the regular season in the eight-year history of Citizens Bank Park. It was the 143rd consecutive sellout, including postseason.

Notes: The Phillies have won 15 of their last 16 series and six straight since last season. ... Dobbs is 3 for 6 with four RBIs as a pinch hitter. ... Victorino made a diving catch to rob Sanchez of a hit leading off the ninth.