Alcides Escobar homered on the game's first pitch. Alex Gordon and Salvador Perez also went deep, and the Royals won after squandering a 4-1 lead.
Mike Moustakas walked leading off the eighth against Pedro Strop (1-3). Cain then drove him in with a double to the base of the wall in right-center and the Royals scored two more thanks to an error by center fielder Dexter Fowler.
He dropped Omar Infante's liner trying to make a shoestring catch with runners on first and second, then fell trying to pick up the ball. Cain and Eric Hosmer scored, making it 7-4.
Kelvin Herrera (1-1) gave up a tying solo drive to Addison Russell in the seventh but picked up the win.
