Orioles 2, Nationals 1 (11): Nick Markakis belted a solo homer in the top of the 11th inning as Baltimore posted its fourth straight victory by winning the opener of the Beltway Series.

After J.J. Hardy flied out to lead off the frame, Markakis deposited an offering from reliever Ryan Mattheus (2-1) into the second deck in right field for his seventh homer. The victory was Baltimore's sixth straight in extra innings.

Adam Jones had an RBI infield single in the first inning to extend his hitting streak to 10 games. Rookie Xavier Avery matched Jones and Markakis with a pair of hits and starter Jake Arrieta tossed seven strong innings for the Orioles, who have won seven of their last nine.

Kevin Gregg (2-1) was credited with the win after tossing one scoreless inning of relief. With Jim Johnson unavailable after pitching three straight games, Pedro Strop secured his third save by retiring the side in the 11th inning.

Ian Desmond led off the sixth inning with a homer and rookie Bryce Harper had a pair of hits for the Nationals, who suffered their first loss in nine one-run home games this season.

Washington starter Edwin Jackson permitted one run on five hits and struck out eight in as many innings. Jackson's lone trouble spot came in the first after Jones' infield single plated Avery for his 15th RBI in 14 games.

Arrieta allowed one run on six hits and matched a career high with nine strikeouts in seven innings. His lone blemish came when Desmond led off the sixth by depositing an 0-1 fastball into the seats in left for his sixth homer of the season.

GAME NOTEBOOK: Jones has recorded three separate 10-game hitting streaks this season. ... Arrieta also recorded nine strikeouts in a 5-0 win over the New York Yankees on May 2. ... Washington learned that its previous rainout versus Miami will be made up as part of a doubleheader on Aug. 3. The original contest was rained out on April 22.