ALLENTOWN - After having not pitched for a little over a month, Roy Oswalt got back to business Wednesday night at Coca-Cola Park.

Oswalt, one of the Philadelphia Phillies' quartet of aces, began his rehab assignment with the Lehigh Valley Iron Pigs last night and showed flashes of his old self. The right-hander allowed just one run on one hit in four innings of work. It was his first action since being pulled from his June 23 start with lower back inflammation.

"The back felt pretty good," said Oswalt, who struck out four on the night. "We will have to see how it feels when I get back home and rest overnight, but overall it felt much better.

"I was trying to work on some pitches and build some stamina. That was the biggest thing tonight and I think it went alright. I will probably throw another one before I get back to Philadelphia."

Apparently Oswalt felt so good that he went over his expected 60-pitch limit. He threw a total of 72 pitches (41 strikes) and hit anywhere between 87 to 91 miles-per-hour with his fastball. The only mistake he made on the night came in the fourth inning when he hung a changeup to Lars Anderson on a 2-0 count. Anderson promptly deposited the pitch into the right field bleachers for a solo homer.

Still, it was the only hit Oswalt surrendered on the night. He worked a 1-2-3 inning in the first and threw 19 pitches in the process. He needed 23 pitches to get through the second due to two walks, but again got out of the inning unharmed.

Oswalt faced his biggest test heading into the third inning. The Iron Pigs sent nine batters to the dish in the bottom of the second and scored three runs thanks to a solo homerun, a hit-by-pitch and a walk with the bases loaded. The inning took roughly 21 minutes and left Oswalt with nothing to do as he sat and watched.

The prolonged wait didn't affect Oswalt, as he came out and proceeded to have his best inning of the night. He needed just 12 pitches (nine strikes) to get through the 1-2-3 inning and didn't allow a ball to leave the infield. The quick frame put his pitch count at 54 and allowed him to throw another inning.

"The guys did a great job that inning," said Oswalt. "They made (Red Sox starter Kyle Weiland) throw over the plate and we were able to get some runs.

"I felt pretty good. I didn't really have any issues pain-wise. Right now it is just about building stamina more than anything. I want to try and get around 100 pitches."

Oswalt will attempt to make one more rehab start on Monday, however it is unclear what Phillies' affiliate he will do it with as all of their minor league clubs are away. The closest team would be the IronPigs, who play in Scranton/Wilkes-Barre.

Vance Worley has pitched well in Oswalt's absence and may hold on to a starting spot for the rest of the year. Kyle Kendrick has also done a decent job filling in for Joe Blanton. While either could possibly give Oswalt extra rest if he were to need it, the competitor in him doesn't think that will be the case.

"Once you get back into the rotation you want to stay there," Oswalt said. "Those guys have been doing great and hopefully they keep it up. But once I get back I want to stay in my spot.

"We have five guys throwing the ball well right now. It's a good thing because then you don't feel like you are the only one out there. Hopefully I can get in there and help out."

Meanwhile, the Pigs won the game 4-1 to increase their North Division lead to four games over the Paw Sox. Ryan Edell picked up the win in relief. He went three-and-two-thirds, gave up two hits while striking out five.

The win sets a new franchise-record for most games above .500 with 19.