Markakis' homer off Ryan Mattheus (2-1) came with one out in the top of the 11th, right after J.J. Hardy flied out to deep center. Pedro Strop came on in the bottom half for his third save to give the Orioles their fourth consecutive victory and eighth straight on the road. The Orioles (26-14) stretched their lead over the Rays to two games in the American League East with the win.
The win improved Baltimore's record in extra-inning road games to 6-0 this season. Are the Orioles real loose in extra-inning games? Manager Buck Showalter wasn't sure if loose was the right word, but said that, well, they've been there and done that.
"It's just a sense of, I don't want to say comfortable, [but it] seems that it's not uncharted territory or something that they're not used to handling," Showalter said. "Hopefully, [we're] trying to make it a season of that. They have a lot of confidence in close games."
This game was close from the start, something to be expected from two young teams with solid pitching staffs.
The Orioles pushed across a run in the first after leadoff hitter Xavier Avery walked, went to third on a Markakis double and then scored on an Adam Jones infield single. Jones' hit deflected off starter Edwin Jackson's foot straight up into the air, and the Nationals (23-16) could only watch as Avery scored while the ball was coming down near the mound.
Jackson shut down the Orioles for the rest of his eight-inning stint, and Washington tied it in the sixth on an Ian Desmond solo homer. But Arrieta kept the Nationals quiet through his seven innings, limiting them to the one run on on six hits -- with nine strikeouts.
The Orioles missed on a number of scoring chances. They went just 1-for-8 with runners in scoring position and stranded six. Still, they kept battling.
"We feel like we're not out of the game until the last out is made," Arrieta said. "I think it has been apparent the last couple of weeks. Even if we are down one or two runs, we feel like we are still in it, even in the eighth or ninth inning."
The Orioles kept getting runners on base but couldn't move them. They left Wilson Betemit on second in the top of the 10th, when Sean Burnett struck out Avery with two outs.
But the Orioles finally broke through in the 11th. Markakis crushed a Mattheus pitch over the bullpen to snap the 1-1 tie.
"I wasn't looking for too, too much there," Markakis said. "I wasn't expecting [the homer]. I was just trying to have a good at-bat and put a good swing on it."
Mattheus said he was trying to get the slider in a little more, but the ball wound up hanging down and in, and Markakis got all of it.
"He got the barrel to it," Mattheus said. "I made a bad pitch. He is a good hitter, and that's what good hitters do with bad pitches."
The Orioles didn't make a lot of bad pitches. After Arrieta, Darren O'Day threw 1 1/3 shutout innings to get into the ninth, and Troy Patton closed out that inning. Winning pitcher Kevin Gregg (2-1) continued his recent streak of good outings with a scoreless 10th before Strop came on in the 11th.
Closer Jim Johnson had pitched three straight games, so Showalter didn't want to use him. Strop ran into some trouble and faced a two-on with two outs jam, but Adam LaRoche topped one in front of the plate. The right-hander pounced on it to throw out the Washington first baseman to end the game.
"I think we've played more innings than anybody in baseball," Showalter said. "That doesn't come as a shock to anybody. Hopefully, it bodes well mentally."