Nationals 5, Pirates 4: Adam LaRoche and Bryce Harper each recorded two hits and two RBIs as host Washington held off Pittsburgh in the opener of their three-game series.

Denard Span, who failed to reach base in 11 at-bats during the Nationals’ sweep of the New York Mets this week to end his 36-game on-base streak, went 3-for-4 as Washington won for the seventh time in nine contests and maintained its six-game lead over Atlanta in the National League East. Tanner Roark (12-7) won for the fifth time in his last six decisions, allowing three runs on five hits over 5 2/3 innings.

Starling Marte belted a two-run homer and Pedro Alvarez also plated two runs as Pittsburgh fell 3 1/2 games behind NL Central-leading Milwaukee but maintained their half-game lead over San Francisco for the second wild-card spot. Charlie Morton (5-12) remained winless since July 2, giving up five runs on seven hits and three walks in a season-low three frames.

LaRoche, who played 375 games with Pittsburgh from 2007-09, continued to haunt his former team when he singled in Asdrubal Cabrera in the first inning. Harper followed with a two-out, two-run flare just over the outstretched glove of Pirates second baseman Neil Walker to cap the three-run opening frame before LaRoche and Wilson Ramos tacked on RBI singles in the third to stake Washington to a 5-0 advantage.

Roark gave much of that lead back in the fourth, however, when Marte hammered a hanging 1-0 slider into the left-field seats and Alvarez doubled into the gap in right-center to bring home another run. Three relievers flawlessly bridged the 2 1/3-inning gap from Roark to Rafael Soriano, who gave up three hits – including a run-scoring single by Alvarez – before stranding the tying run on third in the ninth to record his 29th save.

GAME NOTEBOOK: LaRoche went 2-for-4 on Friday to improve his career batting average against Pittsburgh to .352 – his highest mark against any NL foe. … Morton has been tagged for at least four runs in each of his last four road starts and is 2-8 with a 4.90 ERA in 14 turns away from home this season. … Walker (lower back tightness) started for only the second time in his team’s last 13 games and went 1-for-4 with a run scored out of the cleanup spot.