The Royals won their fifth consecutive game over the Red Sox when Jeff Keppinger's three-run homer broke a tie in the six-run 12th inning that gave Kansas City a 10-4 victory Saturday night.
"The Sox are still a powerhouse, one of the most feared teams in baseball," Kansas City's Mike Sweeney said. "To beat them two straight here is a huge feat. I can't ever remember playing as well as we have against the Red Sox."
Kansas City improved to 54-89 one night after winning 10-9 with two runs in the ninth. Boston fell to 75-67, is 10-24 since Aug. 5 and trails Minnesota by 1½ games in the AL wild-card standings.
The Royals "might not have the record that dictates they should beat us but they have good players over there," Boston's Coco Crisp said.
The winning streak is their longest against Boston since they won six in a row from Aug. 1, 1996 to July 31, 1997.
Kansas City had squandered leads of 2-0 and 4-2 one night after blowing an 8-3 lead when Boston also scored six runs in one inning, the eighth. On Saturday, David DeJesus started the winning rally with a leadoff double off Craig Breslow (0-1).
Manny Delcarmen replaced Breslow and retired Esteban German before walking Mark Grudzielanek intentionally. Then Keppinger, who entered the game in the 10th as a pinch runner, went to the opposite field and just cleared the low fence 302-feet down the right-field line.
"I was looking for something up that I could get out of the infield," Keppinger said. "I was hoping for a sacrifice fly and it turned out to be a lot better."
Keppinger, obtained from the New York Mets organization on July 19, recorded his first hit for the Royals and fourth of his career. His last homer came Sept. 10, 2004 with the Mets.
Delcarmen also struggled Friday night, giving up three runs in 2/3 of an inning.
"I was trying to go down and away. I thought it was a good pitch," he said. "I feel like right now even if I make a good pitch something (bad) happens."
The Royals followed the homer by loading the bases when Ryan Shealy doubled and John Buck and Joey Gathright were hit by pitches. Andres Blanco followed with a bases-clearing double.
Joe Nelson (1-0) picked up his first major league win with 1 1/3 scoreless innings.
"We're young but we're starting to learn how to win the close games," he said.
Before Keppinger's homer, the Royals executed a double steal that put runners at second and third with one out and eliminated the chance for a routine double play.
"You've got a team on the ropes, all of a sudden it turns into a blowout," Boston manager Terry Francona said. "We're holding the runner at second, he takes off, and you know Manny's going to have to realize that it's in the part of the game they can do that. It changes the game significantly."
The Royals took a 2-0 lead on RBI singles by Gathright in the second and Grudzielanek in the third.
The Red Sox tied it in the fourth, when Luke Hudson threw 41 pitches, but wasted a chance for a bigger inning when two runners were thrown out at home. Dustin Pedroia led off with his first homer and Doug Mirabelli added an RBI single.
Kansas City went ahead 4-2 in the fifth against Josh Beckett, scoring on Grudzielanek's groundout and Shane Costa's double.
Boston tied it again in the seventh when Mike Lowell reached second on a walk and a wild pitch and Mark Loretta walked. Pinch-hitter Wily Mo Pena smacked the first pitch for a run-scoring ground-rule double to center and Kevin Youkilis made it 4-4 with his major-league leading 11th sacrifice fly.
The Red Sox wasted opportunities in extra innings, leaving two runners on base in the 10th, one in the 11th and two in the 12th.
Patrice Bergeron, the Boston Bruins leading scorer last season, threw out the ceremonial first pitch. ... German's two doubles gave him three in the first two games of the series. ... Manny Ramirez went 0-for-4 with two strikeouts and is 2-for-16 in five games since returning to the lineup after missing 10 of 11 games with a sore knee. ... Youkilis is one shy of the team record of 12 sacrifice flies accomplished three times, the last in 1959 by Jackie Jensen.