WASHINGTON -- Starter Max Scherzer allowed just one run in eight innings and right fielder Bryce Harper hit a three-run homer in the first as the Washington Nationals beat the slumping Philadelphia Phillies 7-2 on Friday.

The Nationals (5-6) have won three games in a row and scored 29 runs in their last four contests. The Phillies (3-8) have lost six in a row while scoring just 13 runs.

Opening Day starter Scherzer (1-1) -- signed in January to a seven-year, $210 million contract -- got his first win with the Nationals as he gave up just four hits and struck out nine in his third start.

Washington manager Matt Williams noted Scherzer has added a cutter to his arsenal. "If he can control it, it opens up the whole plate for him," Williams said.

Philadelphia starter Sean O'Sullivan (0-1) allowed four runs in five innings before Jeanmar Gomez took over in the sixth. O'Sullivan gave up homers to Harper and infielder Danny Espinosa in his first appearance at Nationals Park.

Philadelphia center fielder Odubel Herrera, the Rule V draft pick from the Texas Rangers, had two hits as the leadoff man. Washington shortstop Ian Desmond had three singles and reached base all five times, although he did make his seventh error in 11 games.

The Nationals grabbed a 3-0 lead in the first inning after right fielder Bryce Harper crushed a 1-2 pitch from O'Sullivan for his third homer of the year. The blast scored third baseman Yunel Escobar, who had singled, and Desmond, who had been hit by a pitch.

The Phillies cut the margin to 3-1 in the third when Herrera tripled with one out and scored on a groundout by shortstop Freddy Galvis.

Washington second baseman Danny Espinosa hit a solo homer to lead off the fourth, giving the Nationals a 4-1 lead.

First baseman Ryan Zimmerman, who made a diving catch of a foul ball in the fifth, had a two-run double in the seventh to pad the Washington lead to 6-1. Zimmerman then scored on a throwing error by second baseman Chase Utley on an infield single by catcher Wilson Ramos.

Washington reliever Felipe Rivero pitched the ninth in his big league debut. He gave up an RBI single with two outs to first baseman Ryan Howard before getting the last out as he fanned left fielder Darin Ruf.

NOTES: Washington 3B Yunel Escobar left the game after he grounded out to short on a close play to end the fourth inning. After Escobar crossed the bag, he held his left thigh. Escobar entered the game batting .282 and his first-inning single extended his streak of reaching base to 10 games. ... The scheduled starters on Saturday are Nationals RHP Jordan Zimmermann (1-1, 8.64 ERA) and Phillies RHP Aaron Harang (1-1, 0.73). ... The Phillies entered Friday with five losses in a row and a .215 batting average. They also were next to last in the National League with 24 runs scored. ... Nationals C Wilson Ramos was tied for the team lead with eight RBIs after games through Thursday. He had driven in a run in five games in a row. ... Philadelphia 3B Cody Asche was hitting .429 at game time, the third-best mark in the National League.