BALTIMORE — Put another one in the let-get-away column.
The Royals built a three-run lead Tuesday night for Zack Greinke but let it slip away in a 4-3 loss to the Baltimore Orioles in 10 innings at Camden Yards.
The loss prevented the Royals from sweeping the two-game series.
Baltimore erased the deficit with two homers by Luke Scott against Greinke before pulling even in the eighth inning on Corey Patterson's homer against Blake Wood.
The end came when Nick Markakis delivered a walk-off single with one out and the bases loaded in the 10th inning against Bryan Bullington.
It was Bullington's first appearance since arriving Monday from Triple-A Omaha, where he compiled a 1.71 ERA in seven appearances.
He retired the first hitter before yielding a single by Julio Lugo through the left side. A walk to Patterson moved Lugo to second.
The Orioles loaded the bases when Bullington missed first base when taking the throw from first baseman Billy Butler on Cesar Izturis' grounder to the right side. It was scored an error.
Markakis followed with a single that curled beyond a shallow-playing Mitch Maier in center field.
The Orioles scored the winning run after the Royals failed to cash a two-on, two-out opportunity in the top of the inning against Alfredo Simon. The threat ended when Jose Guillen struck out.
The Royals went 13 up and down against Orioles starter Kevin Millwood before rousing themselves for five singles in a three-run fifth inning.
Greinke gave two of them back on homers by Luke Scott in the fifth and seventh innings. Still, he handed a 3-2 lead to Wood after seven innings.
Wood served up a one-out homer to Patterson in the eighth that tied the game. Wood had worked five scoreless innings in four previous appearances since arriving from Triple-A Omaha.
Patterson's homer meant no-decisions for Greinke and Millwood. It marked the fourth time in nine starts the bullpen failed to protect a lead for Greinke, who remains 1-4 despite a 2.72 ERA.
Millwood can commiserate. He is 0-4 despite a 3.65 ERA.
Greinke allowed four hits in his seven innings but, as noted, two by Scott left the park. Fortunately, both came with the bases empty. Greinke struck out six and walked one while throwing 108 pitches.
Millwood gave up three runs and 10 hits in eight innings.
The Royals mounted another threat in the eighth when Guillen's two-out double moved Butler to third. Orioles manager Dave Trembley opted to stick with Millwood, who validated the move by retiring Callaspo on a fly to left.