Starlin Castro suffered a Grade 1 hamstring strain on Saturday, which could prematurely end his first season with the New York Yankees.
The injury typically takes two weeks for recovery.
The Yankees have just 13 games remaining after Sunday night's finale against the Boston Red Sox.
"It's hard to say. It really just depends on how quickly he heals," Joe Girardi said. "Hopefully it's not too long. Hopefully it's not more than a week, but still I think that's probably pushing it. But you're hoping that he heals quick."
Castro is New York's leader in hits (153), total bases (246) and RBIs (69), and his career-high 21 home runs are more than any player on the current roster.