The Rays announced that Mahtook will fly to St. Petersburg on Tuesday to be examined by a hand specialist.
"There's no good time to get hurt," Mahtook said. "But it is frustrating. I was getting consistent at-bats and I was feeling good. I thought this was going to be the series when I turned the corner and I finally was going to be consistent with my swing path.
"Things we've worked on the past few days have really started to set in. Then second pitch of the at-bat break my hand. It's not ideal but something we have to deal with and move forward. Hopefully it's a next-man-up kind of situation and guys step up and we keep winning games."
Pearce flew out in the ninth inning and came up lame, grabbing his right hamstring. He told reporters after the game that for now they will take a wait-and-see approach to how they proceed.
"I think that's the initial thing we're going to do for now," said Pearce when asked if he might sit out a couple of days to see if the injury improves before a decision is made.
Pearce said he did not "feel a pop."
"It was a hard grab," said Pearce after limping to his locker. "I wasn't running hard. I still had my strength. There's still some positives going on."
Pearce's loss could be devastating to the offense. He's currently hitting .322 with nine home runs and 25 RBIs.
Once Mahtook is placed on the disabled list, he will join three other Rays outfielders: Kevin Kiermaier (left hand fracture), Brandon Guyer (left hamstring strain) and Steven Souza Jr. (left hip strain).
Mahtook took a pitch off his left hand from Indians starter Josh Tomlin in the top of the second. Mahtook played defense in the bottom half of the inning, but Taylor Motter took over for Mahtook in right field prior to the start of the bottom of the third.
Mahtook is hitting .154 with no home runs and three RBIs.