Ranger manager Ron Washington said Yorvit Torrealba will start Saturday behind the plate.
"I just want to give Mike a day to rest his leg," Washington said.
Napoli was thrown out at the plate in the fifth inning on a slide into Mariners catcher Miguel Olivo. Napoli appeared fine and stayed in the game until the ninth inning, when he was replaced by Torrealba.
"He just told me I might want to put someone else in there who could move a little better," Washington said. "It's not any big deal."