ATLANTA — Pitchers are having a hard time keeping Bryce Harper off the bases — and inside the park.

Harper's hot start is a big reason the Washington Nationals are unbeaten.

The star slugger hit a three-run homer and the quick-scoring Nationals beat the Atlanta Braves 8-1 on Monday night for the first 4-0 start to a season in their Washington history.

Harper's second-inning shot off Sean Newcomb (0-1) to center field gave the Nationals a 5-0 lead. He also drew four walks and scored three runs.

Harper has three homers — including two in his last two at-bats during Sunday's 6-5 win at Cincinnati — and seven RBIs. He reached in eight consecutive plate appearances, two shy of the Nationals record, before grounding out in the ninth.

Harper said he wasn't far off a chance to homer in four straight at-bats.

"I got a pitch I could absolutely drive and just topped it a little bit," he said.

First-year manager Dave Martinez wasn't about to complain.

"He's good. He's one of the best," Martinez said. "I'm glad I get to watch him play every day and hopefully he continues doing what he's doing."

Howie Kendrick's double to right field drove in Harper, who walked, in Washington's two-run first inning.

It marked the fourth straight game as the road team the Nationals scored in the first inning to give their starting pitcher a lead before his first pitch.

This time, the beneficiary was Tanner Roark (1-0), who allowed one run in seven innings. Backed by strong defense, including on third baseman Anthony Rendon's diving stop of Dansby Swanson's grounder in the seventh, Roark gave up four hits with one walk and six strikeouts.

The Nationals stretched the lead in the second.

After Newcomb gave up singles to Pedro Severino and Anthony Rendon, Harper walked to the plate as stadium organist Matthew Kaminski played the somber "Imperial March." Braves fans chimed in with boos.

Harper crushed a first-pitch fastball .

"I was trying to come in more," Newcomb said, adding the pitch instead "was middle and low where he swings."

The homer landed in the decorative rocks behind the 400-foot marker on the center-field wall.

Newcomb allowed six runs, five earned, on five hits and four walks in 4 1/3 innings.

Freddie Freeman's single drove in Ender Inciarte, who singled and stole second, in the fourth.

Nationals pinch-hitter Brian Goodwin had a two-run single off Jose Ramirez in the ninth.