
The Nats (38-24) have won eight of 11, and have taken the first two in the series with the Phillies (29-33).
Roark (5-4, 2.93 ERA) put up seven scoreless innings, allowing six hits, striking out seven and walking one.
Michael A. Taylor (.219/.252/.351) and Clint Robinson (.230/.300/.377) each had three hits filling in for regulars Jayson Werth and Ryan Zimmerman.
Anthony Rendon (.262/.345/.410) was 1-for-4 with a two-run double and two runs scored.