• Royals postseason gear | Schedule
Cain fouled a pitch directly off his right knee cap on Wednesday night. He did not play again until Saturday, when he had three hits -- including two doubles.
"It doesn't affect me swinging," Cain said. "But it's just more on the bases and in center. But I dealt with it last year in the playoffs."
Cain has been told by the team trainers that it will take three or four weeks for the bone bruise to properly heal.
"It'll be barking the whole month," Cain said. "But it's just a matter of pain management. I'll be OK."
Cain had a similar injury last October and was still phenomenal -- he was MVP of the AL Championship Series against Baltimore.
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.