PHILADELPHIA -- It looked like third baseman Ryan Zimmerman was going to miss his fourth consecutive game because of a left hamstring injury, but his two-run pinch-hit homer helped the Nationals defeat the Phillies, 7-5, at Citizens Bank Park on Thursday afternoon.

Zimmerman insisted that the hamstring was getting better, but it appeared doubtful that he would see action Thursday because he never tested the hamstring in terms of participating in running drills. However, he was able to take batting and fielding practice the past two days.

According to teammate Ivan Rodriguez, Zimmerman didn't miss a beat in the batting cage.

"When you see Zimmerman's BP, it's unbelievable. He just hit balls for miles,' Rodriguez said.

Before Zimmerman came to the plate, the Nats were down, 4-2, when they stormed back in the top of the eighth inning against right-hander Danys Baez.

After 25 at-bats, Adam Dunn led off with his first home run of the season and cut the deficit to 4-3. Known as a patient hitter, Dunn decided to swing at the first pitch.

"I basically ambushed him," Dunn said. "I haven't been swinging at the first pitch. The other day, he walked me on four straight pitches leading off the eighth. I knew he was going to try to get ahead. I just closed my eyes and swung."

After Rodriguez walked with one out, Zimmerman came in as a pinch-hit for right-hander Tyler Clippard.

Manager Jim Riggleman told Zimmerman before the inning started that he might get an at-bat in a meaningful situation, and he did. Zimmerman hit a 1-0 fastball over the right-field wall to give Washington a 5-4 lead.

"What else can you say? The franchise did it again," said left-hander Scott Olsen, who gave up four runs in 5 2/3 innings. "For him to sit here for a couple of days and not see live pitching, it pretty remarkable.

Baez appeared surprised that Zimmerman was able to hit the home run.

"I was trying to stay away on him," Baez said. "I've faced him a lot of times. I always stay in, in, in. He's coming off the bench and hasn't played for a couple days, so I was trying to stay on him. He hit the ball and it went out of the ballpark. I didn't hear good contact. I was surprised [the ball went out], myself."

Zimmerman said that taking batting practice the past two days helped him hit the home run.

"It was definitely nice to hit in the cage the last two days," Zimmerman said. "Being able to get into my routine and get some baseball stuff in the last two days definitely helped. I was just happy and be a part of the game. Pinch-hitting is something new to me. You just have to be ready. Hopefully you could do something to help."

The Nationals made it a 7-4 game in the ninth as Rodriguez drove in two runs with a single to left off Ryan Madson.

Washington closer Matt Capps got his fourth save of the season by pitching 1 2/3 innings. It was the first time in his career he was able to pick up a save by pitching more than one inning.

Olsen started and kept them in the ballgame. He was solid during the first five innings, allowing just one run. But things started to unravel in the sixth. With the game tied at 1 and a runner on first with two outs, Olsen had problems throwing strikes. Olsen walked Jayson Werth and Raul Ibanez to load the bases.

Juan Castro came to the plate and singled to right to drive in Placido Polanco and Werth.

Olsen left the game in favor of Clippard. After Carlos Ruiz was walked intentionally, Clippard walked Greg Dobbs to force home Ibanez and make it a 4-1 game.

"I thought I was OK. I ran into some trouble -- too many walks," Olsen said. "I can't walk three guys in a game, especially two in one inning. That just can't happen. Other than the lack of control late in the game, it was OK."

But the Nationals didn't give up as they headed home with a 4-5 record. The team also broke an eight-game losing streak at Citizens Bank Park.

"It means the Phillies have a good club that has been tough on us," Riggleman said. "They are tough no matter where you play them. They are very comfortable here. They are just hard to beat all the way through the lineup. It was a great challenge for our ballclub, and we met the challenge pretty good.

"We are not satisfied being 2-4 against them, but both were tough wins. To play tough ballgames against a hard-nosed tough club like Philadelphia and come out ahead a couple of times -- whether it's tangible or under the surface -- I think it will impact our guys."