Just one week after the first trailer for Teenage Mutant Ninja Turtles debuted, director Jonathan Liebesman's action-adventure has added Johnny Knoxville and Tony Shalhoub to voice the turtle Leonardo and his rat father-figure Master Splinter.

During principal photography, Pete Ploszek played Leonardo and Danny Woodburn played Splinter, but sources indicate that the filmmakers had always considered changing the voices of these characters. We'll have to wait and see who the production hires to voice Raphael (Alan Ritchson), Donatello (Jeremy Howard) and Michelangelo (Noel Fisher).

Paramount has also proved to be a studio that likes to add last-minute additions, with films such as World War Z, G.I. Joe Retaliation and Noah undergoing changes while they were deep in post-production. It isn't known if these changes will affect Teenage Mutant Ninja Turtles' August 8 release date at this time.

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Johnny Knoxville most recently starred in Jackass Presents: Bad Grandpa, and Tony Shalhoub last starred in Pain & Gain, which was directed by Teenage Mutant Ninja Turtles producer Michael Bay.