"He's OK, still day to day," Melvin said before Saturday's game. "I don't want to get ahead of myself. We'll see how he's doing tomorrow."
After hitting his first career grand slam in the first inning Friday, Moss began to experience pain in his right calf prior to the top of the third.
"I was coming onto the field and it just balled up on me, and I couldn't really get the cramp out for the entire inning," Moss said. "It was hurting pretty badly."
Moss entered Saturday with 13 home runs and a team-leading 46 RBIs.
Kyle Blanks, who replaced Moss at first base Friday, got the start at first base Saturday against southpaw Tyler Skaggs.
Aaron Leibowitz is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.