The Battle of the Beltways rivalry gets underway tonight in Baltimore at 7:05 ET, live on MLB.TV. It's been a one-sided affair the past five years, with the Orioles taking each season series over Washington.
In the opener of the four-game set, left-hander Giovany Gonzalez takes the hill for the Nationals and a well-rested Kevin Gausman gets the nod for the O's.
Gonzalez is off to a stellar start through six outings this season. His 1.64 ERA leads the National League and his 7.04 hits per nine innings ranked seventh in the NL. In nine career starts against the Orioles, Gonzalez is 1-5 with a 3.88 ERA.
Gausman tossed just one inning in his last start against the Red Sox after he was ejected for plunking shortstop Xander Bogaerts in a heated series. The righty is looking for his first win since April 13.
The Nationals enter the series with the best record in the NL (21-10), while the O's (20-10) are jousting with the Yankees atop the American League East standings.
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Here's what else to watch for tonight (all times ET):
Tanaka tries to win fifth straight: NYY@CIN, 7:10 p.m.

Yankees right-hander Masahiro Tanaka has been on a roll. He has posted a 2.51 ERA over his past four starts, striking out 18 and walking just four.
Tanaka has never faced the Reds, but in 11 Interleague starts, he's 6-4 with a 2.64 ERA. The only Reds player who's faced him is Scooter Gennett, who's 1-for-2 with an RBI.
Reds right-hander Rookie Davis will face the organization that drafted him. He was one of four players traded to Cincinnati for Albertin Chapman in 2015.
Davis picked up his first career win on Wednesday against the Pirates, tossing five scoreless innings.
Senzatela faces tough test: CHC@COL, 8:40 p.m.

The thin air in Denver has done little to skew the results for Rockies righty Antonio Senzatela. He won NL Rookie of the Month honors for April after going 3-1 with a 2.81 ERA.
Just after earning the award, Senzatela held the Padres to three runs (two earned) over six innings on Wednesday for the win. He has gone at least six innings in his past five starts.
He will face quite the challenge in Cubs right-hander Jacob Arrieta, who tossed his third quality start in his last outing against the Phillies. He allowed three runs on six hits in six innings for the win.
This marks Arrieta's second career start at Coors Field. The last one came on Aug. 6, 2014, with him giving up nine runs over five innings.