Simmons was hurt when he came down awkwardly on his glove hand while diving to stop a grounder hit by Evan Longoria. He immediately left the game.
The Angels later announced Simmons' injury. He will have an MRI on Monday.
Simmons is one of the majors' best fielders. He won two Gold Glove awards with the Braves before they traded him to Los Angeles in the offseason. He has been a strong fielder in his first season with the Angels, though he made a throwing error Saturday in the loss.
Simmons has struggled at the plate in Anaheim. So far, he is batting .219 with eight RBIs. He had a hit Saturday to end an 0-for-21 skid.
The Rays won 3-1 to complete a three-game sweep of the Angels.
Information from The Associated Press was used in this report.