The team said the injury will be re-evaluated Thursday.
A trainer attended to Molina on the field Wednesday night after he slid feet first into third base in the second inning. Molina remained in the game and caught the top of the third before he was lifted for pinch-hitter Tony Cruz in the bottom half.
Cruz then replaced Molina behind the plate.
Molina was voted to his sixth straight NL All-Star team Sunday and is a starter for the fourth time. He doubled in the second inning and was hitting .287 with seven homers and 30 RBIs.