BOSTON -- Kansas City's Lorenzo Cain drew a bases-loaded walk on four pitches with two outs in the 10th inning Sunday night, and the Royals completed a doubleheader sweep of the Boston Red Sox with a 5-4 win.
Kansas City won 4-2 in the afternoon game at Fenway Park, snapping the Red Sox's seven-game winning streak.
"Doubleheaders haven't fared too well for us," said Royals designated hitter Billy Butler. "We haven't won many series here. We were real close to winning all three of them. (But Daniel) Nava had the big hit yesterday and we had the big hits today."
After striking out pinch hitter Miguel Tejada looking, Red Sox left-hander Andrew Miller (0-1) gave up a single to Alex Gordon, then walked Alcides Escobar. Billy Butler struck out before Eric Hosmer singled to load the bases. Miller then walked Cain, giving the Royals what proved to be the game-winning run.
"It was a great at-bat right there," said Royals manager Ned Yost. "He laid off four pitches to plate the winning run. A lot of times guys get over anxious there. He's seeing the ball real well right now."
"Inconsistent strikes," said Red Sox manager John Farrell of Miller's outing. "I thought he made a couple of good pitches to Butler to get the strikeout. And then with the bases loaded, obviously the bases-loaded walk, but kept it there and unfortunately we weren't able to do anything against (Royals closer Greg) Holland."
Kelvin Herrera (2-2) pitched two scoreless innings, giving up a hit and one intentional walk with three strikeouts.
Greg Holland struck out the side in the 10th inning to earn his fourth save.
Royals right-hander Jeremy Guthrie went six innings, giving up four runs on eight hits, including one home run, and four walks with two strikeouts.
Red Sox right-hander Allen Webster started in his major league debut. He went six innings, giving up three runs (two earned), on five hits, including two home runs, and a walk with five strikeouts.
Boston first baseman Mark Napoli went 3-for-4 with two RBIs and a run, falling a triple shy of the cycle.
In the bottom of the fifth, with Daniel Nava on second and Dustin Pedroia on first, Napoli's third hit of the game, a single to center, drove in Nava, giving the Red Sox a 4-3 lead.
Webster got off to a rocky start. Gordon greeted him with a first-pitch double off the wall in left field. Gordon scored when the next batter, Escobar, hit an infield single, with shortstop Pedro Ciriaco committing a throwing error. However, Webster settled down and retired the next three batters.
"It was an experience," said Webster. "The fans were amazing. Once I was out there, it felt good.
"I wasn't expecting a first-pitch swing but it happens. It was good to get my feet wet. Once he got on second, I had to make my pitches and go from there."
The Red Sox got two runs in the second when Napoli led off against Guthrie with his third home run of the season. Jarrod Saltalamacchia followed with a walk, and he scored on Mike Carp's one-out double. Boston added a run in the third when Jacoby Ellsbury doubled and scored on Pedroia's single.
The Royals tied the score in the fifth on solo home runs by George Kottaras, his first hit of the season, and Gordon, his first homer of the season. But the Sox got a run back in the bottom of the inning when Napoli's single scored Nava from second.
But Billy Butler's two-out home run in the eighth off Koji Uehara, his third home run of the season, tied the score, 4-4.
"It's good to tie the ballgame up right there," Butler said. "I definitely haven't been swinging the bat best. It's good to finally get one. It's obvious I'm not in a groove. But I'll get things figured out."
In the first game, Kansas City's Ervin Santana (2-1) went seven innings, giving up two runs and six hits with no walks and seven strikeouts. He is the first pitcher to hold the Sox to two or fewer runs without allowing a walk since Tampa Bay's David Price did so on Sept. 25.
Boston's Ryan Dempster (0-2) went seven innings, giving up four runs and six hits, including a home run, and three walks with eight strikeouts.
NOTES: Ciriaco's first-inning throwing error was the fourth committed by the Red Sox this season and just the fourth by an infielder. OFs Jackie Bradley and Ellsbury and catcher Saltalamacchia have also committed errors this season. ... The Red Sox, Major League Baseball, the players' association and Red Sox fans donated $646,500 to The One Fund Boston to assist those most affected by the bombings at the Marathon finish line on April 15. ... Before his fly ball to left field in the fourth inning was ruled a three-base error, Mike Carp had reached base in his five previous plate appearances with extra-base hits in the last four. ... Ellsbury's double leading off the third inning extended his hitting streak to 11 games. ... With his third-inning single, Pedroia extended a streak of reaching base safely to all 18 games this season and 28 straight going back to Sept. 21. He is the first Red Sox player to reach base in the team's first 17 games of a season since Manny Ramirez did it in the first 23 games in 2001. ... Greg Holland earned saves in both ends of the doubleheader, becoming the first Royals pitcher to do so since Roberto Hernandez on July 15, 2002, against the Rangers. The last major league pitcher to save both games of a doubleheader was Rafael Soriano on Sept. 19, 2012, while with the Yankees against the Blue Jays. ... The Royals hit four home runs combined in the doubleheader. They entered Sunday with just six home runs in their first 15 games of the seasons. Their three home runs in the night cap were the most in a game since hitting three on Sept. 14, 2012 against the Angels.