PAULA ABDUL is thrilled to be joining “Dancing with the Stars” as a guest judge – but the show shake-up is ruffling CARRIE ANN INABA’s feathers!

Carrie Ann, who’s been part of the ABC reality dancing competition since its 2005 debut, doesn’t want to share camera time with the former “Ameri­can Idol” and “X Factor” judge, say pals.

“She thinks Paula’s a tremendous scene-stealer,” revealed a show in­sider. “Carrie Ann loves being the only female judge, and she’s suddenly looking at Paula as competition, even though Paula’s gig is temporary.

“Carrie Ann knows Paula has a loyal fan base and is terrified she’s mov­ing in on her territory.”

“DWTS” regularly features guest judges. Stars such as Kelly Osbourne, Drew Lachey and Emmitt Smith have shared the spotlight with Carrie Ann and fellow judges Bruno Tonioli and Len Goodman. But adding Paula to the mix seems to have struck a nerve with Carrie Ann.

According to the source, the 44-year-old – who re­cently split from fiance Jesse Sloan – has already begun taking pot shots at Paula. Carrie Ann reportedly called Paula, 50, a “failure” for being dumped from “Idol” and “X Factor.” And she poked fun at Paula’s own reality effort, “Live To Dance,” which was canceled after just seven episodes.

Of course, it probably doesn’t help that Paula has made it known she’d love to become a permanent fixture on “DWTS.”

“Paula loves the spotlight and has a stellar track record because audiences go for her in a big way,” the source said. “If the producers ask her to stay – she’ll say yes with no hesitation.

“That would be Carrie Ann’s worst nightmare.”