Nationals batter Pirates, 8-4

PITTSBURGH — Bryce Harper belted his 13th home run, Ryan Zimmerman smacked a two-run double to add to his major league-leading RBI total and the Washington Nationals held off the struggling Pittsburgh Pirates 8-4 on Tuesday night.

Harper’s laser to the last row of seats in right field in the ninth gave the 24-year-old star a home run in every ballpark in the National League. He finished with two hits to move ahead of Zimmerman for the major league-lead in batting average (.388).

Zimmerman had two hits, including a double in third inning that gave him 38 RBIs on the season. Jayson Werth added three hits and is batting .457 (16 for 35) in his last nine games.

Stephen Strasburg (4-1) allowed three runs in six-plus innings, walking one and striking out three on a night he didn’t have his best stuff.

Josh Harrison had two hits for the Pirates, including his sixth home run of the season, and also avoided a tag at second base with an acrobatic slide in the sixth. Chad Kuhl (1-4) remained winless since the first week of the season.

The Nationals are in the process of running away with the NL East not even a quarter of the way into the season thanks to the best offense in baseball. The lineup wasted little time getting to Kuhl, who hasn’t won since beating Atlanta six weeks ago.

Trea Turner led off with a double and scored on Werth’s RBI single. Strasburg led off the third with a single, moved to second on a single by Werth, and Zimmerman followed one batter later with a double that put the Nationals in front 4-1. Michael Taylor tripled with one out in the fourth, and Wilmer Difo, who came in batting just .196, sent Kuhl’s pitch to the seats for his first of the season to make it 6-1. Kuhl’s ERA ballooned to 6.69 in eight starts.

Strasburg never appeared to get settled. Harrison turned an 89 mph slider into a moonshot to the left field bleachers in the first and Pittsburgh made solid contact throughout Strasburg’s 108-pitch outing. He exited after allowing a leadoff double to Josh Bell and walking Francisco Cervelli in the seventh.

Enter Washington’s bullpen, which began the day with a 5.53 ERA, third worst in the majors. Matt Albers and Oliver Perez came on and didn’t retire any of the three combined batters they faced, thanks in part to a throwing-error by Zimmerman. Pittsburgh closed within two on Adam Frazier’s RBI single before Blake Treinen — who began the season as the closer before being demoted — got Harrison to hit into a double play, then struck out Andrew McCutchen to end the threat.

The strikeout dropped McCutchen’s batting average to .206. The five-time All-Star was removed as part of a double switch in the eighth.

Harper drilled Wade LeBlanc’s pitch with one on in the ninth to give the Nationals some breathing room.