Tigers manager Jim Leyland said that Casey would possibly serve as designated hitter for Game 2 on Sunday at Comerica Park, and he could return to first base for Game 3 in St. Louis on Tuesday night.
"He will," Leyland said. "Unless something goes wrong these next two days, he will play first base in St. Louis on Tuesday night. So everything looks OK, and he will play first on Tuesday."
Casey suffered a small partial tear of the fascia tissue in his left calf while attempting to run out a ground ball in the sixth inning of Detroit's victory over Oakland on Oct. 10. He hasn't played since then and has been receiving treatment for the injury.
Casey was cleared to make his World Series debut at designated hitter for Saturday's game. The Tigers will monitor his situation closely.
"You're never sure with the cold weather -- it's going to be a little uncomfortable for everybody the next two days, [and] tomorrow doesn't look very good at all," Leyland said. "Unless something happens, he'll be the first baseman Tuesday night."
Casey was in the lineup in the No. 7 spot, behind catcher Ivan Rodriguez and in front of third baseman Brandon Inge. Shortstop Carlos Guillen, who has filled in at first base during Casey's absence, was the starter at first base on Saturday night.
With the exception of Casey in the No. 7 slot instead of Alexis Gomez, the Detroit batting order was the same one Leyland used in Game 4 of the ALCS last Saturday, with center fielder Curtis Granderson leading off, followed by left fielder Craig Monroe, second baseman Placido Polanco, right fielder Magglio Ordonez, Guillen, Rodriguez, Casey, Inge and Santiago.
Jim Molony is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.