The first baseman didn't start Wednesday night's game against the Chicago White Sox because of a dislocated ring finger on his left hand.
Napoli was injured during a headfirst slide on Tuesday.
''I'm definitely tender, which was probably expected with what I did to it,'' he said. ''I'm doing treatment, trying to get that swelling out of there. It's feeling better and better as I go. I'm going to do as much treatment on it as possible.''
Napoli wasn't sure when he would be able to return, saying he would see how he feels each day.
''Maybe I can have some late-inning defense or something,'' he said. ''It's sore, but once I get that swelling kind of drained out, it will be better.''
Pedroia missed two starts at second base because of inflammation of the left wrist and had a cortisone shot. He was a pinch runner Tuesday, and doubled and scored in his first at-bat Wednesday.