Both Nationals manager Matt Williams and Orioles manager Buck Showalter stayed with their starters from last night's rainout.
Left-hander Gio Gonzalez takes the mound for Washington after going 2-0 with a 1.47 ERA over his last three starts. He matched his career high with 12 strikeouts in a 12-2 win over the Phillies last Wednesday.
Gonzalez started the Nats' lone loss in Baltimore before the All-Star break, but left in the seventh with a one-run lead before the Orioles tied the game in the eighth and then won on Jonathan's Schoop's walk-off homer off Tanner Roark in the ninth.
The Orioles send right-hander Ubaldo Jimenez to the hill with an 11-9 record and 4.31 ERA on the season.
For the Orioles:
3B Manny Machado
1B Chris Davis
RF Steve Pearce
2B Jonathan Schoop
C Caleb Joseph
SS J.J. Hardy
CF Junior Lake
RHP Ubaldo Jimenez
For the Nationals:
2B Anthony Rendon
3B Yunel Escobar
RF Bryce Harper
LF Jayson Werth
1B Clint Robinson
SS Ian Desmond
CF Michael A. Taylor
C Jose Lobaton
LHP Gio Gonzalez