Withrow appeared in just one Cactus League game this spring as he was battling a back injury.
Greinke had no elbow discomfort on Wednesday while pitching in his first game action in nearly three weeks.
Aaron Harang switched numbers from 44 to 41 this season for the Dodgers, thanks to an old friendship with Reds legend Joe Nuxhall in Cincinnati.
Federowicz spent his last two Septembers mostly watching and learning what it takes to catch in the big leagues. Now, he'll get his chance with the Dodgers as their backup catcher in 2013.
The Dodgers will know more once they get the results of an MRI, scheduled to be performed Wednesday afternoon in Phoenix.
Zack Greinke won't be in Surprise with the Dodgers, but Yasiel Puig will, batting seventh and playing right field against the Royals.
Manager Don Mattingly, general manager Ned Colletti, and Puig himself weigh in on the latest exploits of the 22-year-old, .500-hitting Cuban outfielder with no spot to play on the big league club. Yet.