Michel Hernandez, who was competing for the backup catching job, will miss the next four to six weeks with a fractured right index finger.
The competition is down to Chad Moeller and Craig Tatum.
Hernandez suffered the injury while blocking a ball in the dirt. He got three at-bats Saturday in Tampa, but he couldn't throw the next day. X-rays revealed the fracture.
Trembley said the club might add a catcher, along with some other players, for Saturday's split-squad game.