Eric Hosmer highlighted a six-run sixth inning by providing the go-ahead hit and the surging Kansas City Royals claimed their 15th win in 17 games with a 9-6 victory over the Boston Red Sox.
The Royals began their rally from three runs down against Boston starter Jake Peavy, then moved in front for good on Hosmer's two-run single off reliever Drake Britton (1-1).
Alcides Escobar, David Lough, Billy Butler and Justin Maxwell each contributed an RBI during the breakthrough inning. Maxwell and Alex Gordon both homered earlier in the contest, helping Kansas City take the first two of this four- game set.
"We struggled in the first half offensively, but in the second half we've been real good and we're just trying to stay consistent," said Butler.
Peavy, making his second start in a Red Sox uniform, was charged with six runs on 10 hits over five-plus innings. Mike Napoli had a three-run double and David Ortiz hit a solo homer in the setback.
Napoli's bases-clearing shot off the bottom of the center field wall in the fourth snapped a 3-3 tie to provide Boston with a three-run advantage.
Peavy had settled down after serving up Gordon's third-inning homer that tied the contest, but then unraveled in the sixth when he allowed three straight singles, the last of which drove in a run on Escobar's hit to right.
Britton came in from the bullpen and promptly walked George Kottaras to load the bases. Lough then lifted a one-out sac fly to make it 6-5 before Hosmer delivered the go-ahead blow with a two-run single to left.
Butler then doubled in a run off reliever Pedro Beato, and after Gordon was walked, Maxwell capped the frame with an RBI single for a 9-6 lead.
"We just couldn't stop the momentum in the sixth," said Boston manager John Farrell.
The Red Sox never got a threat going from there and Greg Holland struck out a pair in the ninth to notch his 31st save.
Francisley Bueno (1-0) tossed 2 1/3 innings in relief of Ervin Santana, who was lifted after yielding Napoli's three-run double. He was rocked for six runs and nine hits over 3 2/3 frames.
Daniel Nava drove in a run in the first to put the Sox up 1-0, but Maxwell countered by beginning the second with a homer. Lough knocked in a run later in the frame to put the Royals ahead.
Boston retook the lead in the third, with Ortiz smacking his 22nd homer and Jarrod Saltalamacchia doubling in Stephen Drew to make it 3-2 Red Sox.
The Red Sox lost for just the 10th time in 56 situations this season after scoring the game's first run ... Drew went 1-for-5 and has an 11-game hitting streak ... Kansas City will go for its seventh consecutive series win on Saturday.