Mike Moustakas' early RBI double proved to be the difference, and Greg Holland dodged a bullet in the ninth, as Kansas City clipped Baltimore, 3-2, in the second test of a four-game series.
Eric Hosmer collected a pair of hits and Chris Getz also drove in a run for the Royals, who have won three of their last five.
Bruce Chen (4-0) scattered three hits and one run with four strikeouts over six innings to remain unblemished in 2013.
Holland picked up his 25th save, but not without some effort. Nick Markakis singled to start and scored on Adam Jones' triple to the gap in left center, but Chris Davis fanned swinging, J.J. Hardy grounded to third and Henry Urrutia grounded to first to end the game.
"It's just one of those things that happens sometimes and if you are fortunate enough to get out of it. That's a big win for us and hopefully that can propel us these next few games and win the series," said Holland about the ninth- inning.
Manny Machado hit a solo homer for the Orioles, whose five-game win streak came to a halt. Jason Hammel (7-7) was tagged in the loss for 10 hits and three runs, walking four and fanning four over his six-inning outing.
"We came in and put ourselves in a situation to tie the game off Holland, who's obviously an All-Star. I looked at his numbers, he's got some great numbers. He got himself in a little jam, but he was able to get out of it with some strikeouts and big outs. At the end of the day, we put ourselves in that situation," said Baltimore manager Buck Showalter on their inability to score.
The Royals picked up single runs in their first two turns at the plate, with Billy Butler grounding into a double play with the bases loaded in the first and Getz hitting an RBI single in the second.
Machado's two-out solo shot in the third put the O's on the board, then the hosts countered in the home half. Lorenzo Cain and Butler singled, then Moustakas doubled in Cain for a 3-1 advantage.
Chen retired the final 10 Orioles he faced following Machado's homer, then Kelvin Herrera stranded a runner on third in a scoreless seventh.
Aaron Crow worked around a one-out walk to Taylor Teagarden and kept Baltimore off the board in the eighth.
Chen lowered his earned run average to 1.97 with the effort, and hasn't suffered a defeat since last October 1 against Detroit ... During the game, the Orioles announced the acquisition of reliever Francisco Rodriguez from the Milwaukee Brewers in exchange for infield prospect Nick Delmonico ... Hammel fell to 0-5 with a 5.47 ERA in eight starts since his last win, on May 27 against the Nationals.