WASHINGTON -- Starting pitcher Jerad Eickhoff was on first base when left fielder Aaron Altherr lined a single up the middle with the bases loaded in the third inning.

"He was pretty close to me. I thought I better get going," Eickhoff said of the speedy Altherr, who rounded the bases for an inside-the-park grand slam to give the Phillies a 6-1 lead after center fielder Michael A. Taylor couldn't come up with a shoestring catch.

"We caught a break. That got us going," said Pete Mackanin, the Phillies manager.

Rookie Altherr added a traditional homer in next at-bat and finished with four hits and five RBIs as the Philadelphia Phillies beat the Washington Nationals 8-2 on Friday and pushed the defending National League East champions to the brink of elimination.

"You better make sure you catch it," Altherr said of the miss by Taylor. "He thought he could get it. He is a good fielder. I was thankful I got it past him and was able to score."

The Nationals (78-75) are 8 1/2 games behind the first-place New York Mets as they lost at home for the eighth time in 11 games and fourth straight. The setback came against a Philadelphia team (58-96) that is now 25-43 against divisional foes. The magic number is one for the Mets going into Saturday.

Washington was done in by the 24-year-old Altherr, who was born in Germany, grew up in Arizona and entered this year with just five big league at-bats and was hitting .225 at game time.

"I'm just thankful I put a good swing on it," he said of his second homer, in the fifth. "I just happened to get it up in the air. I felt pretty good yesterday but didn't get a hit."

The last inside-the-park grand slam in the majors was hit by Tampa Bay's Randy Winn against the New York Yankees on Oct. 3, 1999. The last time the Phillies had an inside-the-park grand slam was by Ted Kazanski on Aug. 8, 1956, at the Polo Grounds against the New York Giants.

"I mean sometimes it's a tough call," said Taylor, the center fielder. "Right there I felt like I had a good bead on the ball and thought I had a chance at it. In that situation you better catch the ball and I wouldn't have gone for it if I didn't think I could. Still a bad play once I miss it. It's a tough play."

Cody Asche, the Phillies third baseman, hit his team's fourth homer of the night -- a two-run shot against Rafael Martin -- to make it 8-2 in the eighth.

The winning pitcher was Eickoff (2-3), who gave up just two runs and five hits with 10 strikeouts and one walk in seven innings.

He struck out right fielder Bryce Harper three times, and the MVP candidate was hitless in four at-bats and has gone four games in a row without a hit.

"I had three good pitches working tonight. He is a great hitter," Eickhoff said of Harper. "I was just fortunate to get some pitches in the right location."

The losing pitcher was Jordan Zimmermann (13-9), who had not lost in his previous seven starts and had not lost at home since June 17, against Tampa Bay.

Altherr hit home runs in the third and fifth against Zimmerman, a pending free agent.

"Obviously Altherr had an outstanding day. He swung the bat extremely well," Mackanin said. "We swung the bats well, especially off of Zimmermann. He is a good pitcher."

Zimmermann, 29, was bothered by a sore neck earlier this week but started on regular rest Friday. It would not be his night, as he allowed six runs, six hits (three homers) and two walks with six strikeouts in five innings before he was lifted for a pinch-hitter. It was the third time this year he gave up three homers in a game.

"Feel good," he said of his career in Washington. "Feel like I took the ball every time they asked, did what I could. Some days I didn't have it, some days I was good. I'm not saying this is my last start. You don't know what's going to happen this offseason so we'll see what happens."

NOTES: The Nationals appealed a three-game suspension handed down Friday to RHP Jonathan Papelbon, who was available on Friday. Acquired in a trade from the Phillies in late July, Papelbon was ejected on Wednesday when he hit 3B Manny Machado of the Baltimore Orioles in the ninth inning after Machado hit a go-ahead homer in the seventh off RHP Max Scherzer. "I know he's appealed," Washington manager Matt Williams said of his closer. "We'll go through that process." ... Washington RHP Stephen Strasburg (10-7, 3.81) will face Phillies RHP Aaron Nola (6-2, 3.84) on Saturday. ... The Phillies began their last road series of the year with a record of 24-54 on the road, the worst mark in the majors and the most road losses in a season for the team since going 27-54 in 1988.