SAN FRANCISCO -- Marlins shortstop Hanley Ramirez was replaced in the fourth inning on Wednesday night, an inning after he appeared to jam his right thumb while stealing second base.

The Marlins said Ramirez has a right thumb contusion. He is listed as day-to-day.

An X-ray on Ramirez's thumb came back negative, and manager Fredi Gonzalez said it is 50/50 that the shortstop will play on Thursday.

Ramirez, the 24-year-old All-Star, singled to open the third, and he stole second base with a head-first slide. On the play, the ball appeared to strike him on the thumb, and he remained hunched over at the base as assistant trainer Mike Kozak and Gonzalez raced onto the field.

After having his hand checked, Ramirez remained in the game. He was in the field in the bottom of the third inning.

Alfredo Amezaga replaced Ramirez at shortstop in the bottom of the fourth inning.

Ramirez is batting .297 on the season with 27 home runs and 56 RBIs.