BOSTON (AP) - Kansas City Royals manager Ned Yost said he felt his team always had a chance, even after falling behind by six runs after four innings.

He must have taken a look at the Red Sox bullpen.

Tony Abreu singled home the go-ahead run in the 12th inning, and the Royals completed their comeback from a six-run deficit by beating Boston 10-9 on Saturday night.

"When you battle back from being down six runs, that's a good win," Yost said. "I don't know how you sum it up, but I never felt like we were ever out of that game. A bloop here and a bloop there, a ball in the gap. That was a pretty darn good two-out rally there and again in the 12th."

Just a few hours after Boston traded scheduled starter Josh Beckett to the Dodgers along with Adrian Gonzalez, Carl Crawford and Nick Punto, the Royals scored three runs before substitute starter Aaron Cook got a single out. The Red Sox took a 9-3 lead after four innings thanks to four hits from Gonzalez's replacement, Mauro Gomez, including his first major league homer.

But the Royals made it 9-all with six runs in the seventh - all of them with two outs, including a game-tying, two-run triple by Mike Moustakas that was his first hit in 19 at-bats.

"It was frustrating," Red Sox manager Bobby Valentine said. "We couldn't get that third out in the seventh inning. Had about four tries."

Francisley Bueno (1-0) earned his first major league win after coming in with runners on first and third and one out in the 10th and pitching out of trouble. Greg Holland pitched the 12th for his seventh save.

Junichi Tazawa (0-1) took the loss. He was filling in for Alfredo Aceves, who was suspended three games a day after storming out of Valentine's office because he was passed over for a save opportunity.

"Might have had something to do with that," Valentine said after Saturday night's game. "I'm a little disappointed. You just have to know the difference between right and wrong. That's all we ask."

Alex Gordon drove in four runs and Billy Butler had three hits for the Royals, who had lost three of their previous four games.

Mike Aviles hit a three-run homer for Boston, which had a season-high 20 hits on the day it essentially conceded the season by sending three of its highly paid but underperforming stars to Los Angeles in a salary purge that will save more than $250 million through 2018.

Hours after the deal was confirmed, Cook spotted the Royals a 3-0 lead before the Red Sox rallied back. Gomez started things with a solo homer in the four-run second, added a two-RBI single in the three-run third and singled in another run as Boston took a 9-3 lead in the fourth.

NOTES: The Red Sox activated LHP Felix Doubront from the 15-day disabled list, placed OF Daniel Nava on the 15-day DL with a left wrist sprain and recalled SS Jose Iglesias, OF Che-Hsuan Lin and Tazawa from Triple-A Pawtucket. Doubront is scheduled to start on Sunday. ... The Red Sox played several moon-related songs between innings on the day Neil Armstrong, the first man to walk on the moon, died at 82. ... Boston-area Olympians were honored before the game, including judo gold medalist Kayla Harrison and gymnast Aly Raisman. ... Plate umpire Jerry Layne took a foul ball off his mask in the seventh and needed a second to gather himself.