Sources tell Us Weekly that the actresses are "always icy to each other" ever since Rivera reportedly complained to producers about Michele holding up a scene to deal with a personal issue on Tuesday, March 15.
"Naya is jealous that Lea is the show's main star," the insider said. "There is a lot of sighing and eye-rolling between them."
"They talk behind each other's backs -- a lot," said another source.
Last week multiple news outlets reported that Michele and Rivera got into an altercation on the set of their hit show. While one version of the story claimed that Michele stormed off after learning about Rivera's complaints, another said Rivera appeared to be in bad shape since she arrived on set on March 15.
Neither of the actresses nor FOX has addressed the rumors regarding the alleged altercation.