The veteran outfielder will look to improve his .143 average on the season.
Adam LaRoche will also get a day off, with the right-handed hitting Tyler Moore starting at first base.
LaRoche has been nursing an oblique issue for much of the season and also fouled a ball off his right foot a little over a week ago. Against a lefty, manager Davey Johnson apparently feels this is a good time to give LaRoche a breather.
Matt Moore was expected to be one of the top young pitchers in baseball this season, but he's had somewhat of a rough start, going 4-5 with a 4.16 ERA.
Tonight, he'll face a Nats lineup which has struggled recently, however.
For the Nationals:
2B Danny Espinosa
CF Bryce Harper
3B Ryan Zimmerman
RF Michael Morse
SS Ian Desmond
1B Tyler Moore
LF Xavier Nady
C Jesus Flores
P Gio Gonzalez
On the minor league level, Hagerstown Suns righty Alex Meyer has been named one of the players who will participate at the Futures Game during the All-Star festivities in July.
Meyer, a 2011 first-round pick out of Kentucky, has put up a 6-3 record with a 3.33 ERA at low Single-A this season. The 6-foot-9 righty has struck out 77 batters in 70 1/3 innings.