An error by shortstop Jose Reyes with two outs in the ninth led to the game- tying run and the Royals scored twice in the 10th off Todd Redmond (0-4) to win it. Alcides Escobar singled and Pedro Ciriaco was hit by a pitch to put two on with no outs in the 10th. Nori Aoki moved the runners with a sacrifice bunt for Omar Infante, whose liner to left knocked in both runners.
The loss spoiled another brilliant performance by Encarnacion, whose 15th and 16th home runs in May tied him with Mickey Mantle for most in the month in American League history. This was the slugger's fifth multi-home run game in May after hitting just two homers total in April.
Jose Bautista also went deep for Toronto, which had won nine straight and 12 of 13 coming in.
All nine Royals starters had at least one hit as their four-game losing skid was halted. Salvador Perez hit a solo home run, Infante drove in three runs and Escobar had three hits.
Encarnacion clubbed a pair of two-run homers in the fourth and sixth innings, each of which gave the Jays a lead. His no-doubter to left with Adam Lind on first in the fourth made it 4-2. The Royals pushed three across in the fifth to take a 5-4 lead, but Encarnacion restored the Toronto margin with another upper deck shot one inning later.
Casey Janssen took the hill for Toronto in the ninth looking to nail down the save and induced a quick Eric Hosmer grounder for the first out. Billy Butler then roped what looked to be a single into right field, but Bautista charged the ball and fired to first, in time to nab Butler. Alex Gordon looped a broken-bat single into center to keep the game alive, and the speedy Jarrod Dyson pinch-ran and stole second. Janssen then got Perez on a routine grounder to short, but Reyes' throw to first bounced in and out of Encarnacion's glove, allowing Dyson to score the tying run.
Davis retired the side in order in the bottom of the ninth to force extras.
Bautista's two-run shot to right gave the Jays an early 2-0 cushion in the first frame. Kansas
City tacked on a run in the second on Perez's shot and one in the fourth on Gordon's RBI ground rule double to left to tie it.
Escobar started Kansas City's three-run fifth inning with a single and scored on Ciriaco's double to center one batter later. Aoki put runners on the corners with a bunt single, and Infante dropped a single into left to tie it before Toronto starter R.A. Dickey had recorded an out.
Hosmer flied to left for the first out, but Butler had the Royals in front with his RBI single before two more flyouts ended the frame.
Dickey lasted five-plus innings after surrendering five runs on 10 hits, while Shields served up all six Toronto runs and eight hits in seven innings of work.