The Red Sox combined for 20 hits without slugger David Ortiz, but it wasn't enough. Ortiz was sidelined with soreness in his right Achilles tendon one game after returning from the disabled list.
"Today was a crazy day, but it's kind of the business part of it and we realize that things are going to happen throughout the season that we can't control," said starter Aaron Cook. "We came out today, we played really good baseball, we battled our butts off all night. We'll clean up, come back [Sunday] and try to do it all again."
Boston led, 9-3, after four innings. But the Royals stormed back to tie the game at 9 with six runs in the seventh inning. Kansas City sent 10 men to the plate in the frame and scored all of the runs with two outs.
"It was frustrating," Red Sox manager Bobby Valentine said. "We got a lot of hits, we had some opportunities to score some more runs, but just misfired a little and couldn't get the third out in the seventh inning. We had four tries on it and they got RBIs on all of them."
Mauro Gomez led the way in a losing effort with four hits and three RBIs. The rookie launched his first Major League homer in his first at-bat. Not a bad way to replace Adrian Gonzalez -- who was in that deal with the Dodgers -- at first base.
"Gomez had a really nice game, his first home run and a few other hits," Valentine said. "He's a good hitter."
Pitching on three days' rest, Cook gave the Red Sox six solid innings. He replaced Josh Beckett, who also was shipped to Los Angeles. Cook asked Valentine and pitching coach Randy Niemann on Friday night if he could fill Beckett's spot if the trade went through.
"They were cool with it, it all worked out," Cook said.
Cook settled in after a rocky first inning. He gave up three runs in the first, but didn't allow more than one base runner in any of his last five frames. The sinker-baller got 11 outs on the ground.
"The adjustment was just getting the ball down maybe an inch or two more," Cook said. "I just stayed focused down in the zone, didn't try to do too much. I knew I was on short rest and just tried to work quick."
The right-hander rebounded nicely from a rough outing on Tuesday against the Angels, when he allowed five runs over five innings.
"It was more than we expected," Valentine said. "Cook got his ground-ball double plays when he had to and gave us everything he had,  pitches and six innings is pretty good."
Down 3-0 after the first, the Red Sox stormed back to take the lead in the second.
Gomez led off the inning with an arching homer over the Green Monster. Mike Aviles followed with a three-run blast into the Monster seats against his former team. It was the second homer in three games for Aviles.
Gomez added an RBI single in the third as Boston scored three runs to take a 7-3 lead. He wasn't done, though, and his single in the fourth scored Jacoby Ellsbury.
But the Royals took the air out of the ballpark with their six-run seventh.
"I never felt that we were out of that game," Kansas City manager Ned Yost said. "In this park, you can pick up runs in a hurry."
Red Sox outfielder Cody Ross twisted his right knee in the seventh inning on a two-run triple by Mike Moustakas. Ross stumbled as he attempted to make a play on the ball. He was removed from the game after the inning.
"I'm fine. I slid and just kind of tweaked my [right] knee," Ross said. "I'm fine, though. Bobby took me out for precautionary reasons, I came in iced it."
Ross said that he's twisted the same knee in a similar manner before and he does not expect to miss any time.
The Red Sox threatened in the eighth, but couldn't break the tie. Scott Podsednik singled to start the inning, but Dustin Pedroia scorched a liner that was caught by first baseman Eric Hosmer for a double play. Ellsbury doubled off the Monster and stole third, but Ross flied out to end the chance.
Boston had another opportunity to win in the 10th with Pedro Ciriaco on third and one out. But Hosmer threw out Ciriaco at home after fielding a grounder. Che-Hsuan Lin, recalled from Triple-A before the game, struck out to end the threat.