KANSAS CITY, Mo. -- Seems like old times for the Kansas City Royals.

After failing to mount much offense off Washington starter Tanner Roark through the first seven innings, the Royals scored one in the eighth and three in the ninth to claim a dramatic 7-6 victory Tuesday night at Kauffman Stadium.

It was just the second walk-off win of the season, after making it their usual method of operation in the past two seasons, when they won back-to-back American League championships.

Lorenzo Cain hit a game-winning single, capping the Kansas City Royals' three-run, ninth-inning rally off Washington closer Jonathan Papelbon.

"I tried to shorten up my swing, not do too much, just put it in play," Cain said. "I've definitely been struggling. This definitely helps a lot. Hopefully it turns it around for me."

Alex Gordon got an "excuse-me" hit against the shift to lead off the ninth against Papelbon (0-2). Gordon went to third on a long single to left from Salvador Perez, who gave way to pinch runner Terrance Gore. Gore stole second on the first pitch. Omar Infante then struck out, but pinch-hitter Mike Moustakas hit a two-run single to tie the game.

"Every game is important, but we've been scuffling as a team scoring runs,"Cain said. "(We broke) out in a huge way tonight. We've played a lot of games like that, so once Moose came through with that knock to tie the game, we felt like it was ours."

After Jarrod Dyson flied out to left, Alcides Escobar got his fourth hit -- matching a career high that he reached six previous times -- to advance Moustakas to third.

Cain rammed a line drive just beyond the reach of center fielder Michael Taylor, and the comeback was complete.

The win was especially big for Escobar and Cain, both of whom have struggled early this season. Escobar now is 8 for his last 14, after entering Tuesday's game hitting just .234. Cain, who came in hitting .231, went 2-for-5.

"It was a really good night for me and for the team," Escobar said. "I've been working every day. I feel much better. Everybody knows how good this team is."

The Nationals got a big sixth inning off the usually reliable Kansas City bullpen. Kansas City entered the sixth with a 3-2 lead, but the Nationals tagged Luke Hochevar for three runs on four hits before he was pulled.

"Hoch came in and did a great job getting Harper out (to close the fifth)," Yost said. "He kind of centered a couple of pitches the next inning."

The Royals had their own three-run inning in the third off Roark, but they couldn't do much more damage. Roark gave up four runs (three earned) in 7 1/3 innings, allowing six hits, walking two and striking out four.

After Hochevar got out of a bases-loaded jam -- not of his own doing -- in the fifth, he created his own trouble in the sixth. He gave up a leadoff single to Ryan Zimmerman and a one-out single by Jayson Werth that moved Zimmerman to third. Ramos then hit a ground-rule double to right to tie the score.

Danny Espinosa's groundout to second scored Werth. Chris Heisey's triple off the center field wall scored Ramos and chased Hochevar. Werth greeted the fourth Royals pitcher, Dillon Gee, with a leadoff home run in the eighth to give the Nationals a 6-3 lead.

That usually would be good enough for the Nationals' trusted bullpen, but manager Dusty Baker saw a tough one get away.

"It was very tough," he said. "I don't know what to say. It was a situation where we had two strikes, under hitters and started out with a checked swing, which gave them some life, big time. I think two of the hits were two-strike hits. Boy, that one was really tough."

The Royals mounted a threat in the eighth. Escobar singled with one out and went to second on a passed ball. He advanced to third on a bloop single by Cain. Eric Hosmer hit a sharp grounder up the middle that was fielded by Espinosa, but the shortstop only recorded the out at second as Escobar scored.

Chien-Ming Wang (1-0) faced threw a scoreless top of the ninth to pick up the win.

The Nationals jumped out to a 1-0 lead on Anthony Rendon's home run. The Royals answered with three in the third. But Washington came storming back, eventually grabbing the 6-3 lead.

Daniel Murphy got one of the runs back in the fourth on a 416-foot blast to right field. The Nationals loaded the bases with two outs in the fifth off Royals starter Chris Young, but Hochevar got Harper to ground out to Escobar, who tapped second for the force out to end the inning.

NOTES: Royals 3B Mike Moustakas was held out of the starting lineup for the second straight night with swelling in his left thumb. Manager Ned Yost said Moustakas hurt it originally in Los Angeles on the beginning of the last road trip, then aggravated it later in Seattle. Moustakas provided a key pinch single in the ninth inning Tuesday. ... ESPN reported that Nationals OF Bryce Harper signed a 10-year extension on his endorsement deal with Under Armour that is believed to be the largest in history for a baseball player. ... Nationals manager Dusty Baker took a contingent of his players to the Negro Leagues Baseball Museum. Baker wanted his younger players to "let history teach them what happened in the past," he said. "There's always something new that you learn, even though I've been there quite a few times."