Lisa Vanderpump Already Clashing With 'RHOBH' Newbie Denise Richards: 'She's A B***h!'

Denise Richards is joining the cast of The Real Housewives of Beverly Hills for season 9 and RadarOnline.com has exclusively learned she's already butting heads with show veteran Lisa Vanderpump .

"Lisa is fuming over Denise joining the cast and the two of them are definitely going to be going at it," a source close to Vanderpump, 57, said.

"She feels like Denise is trying to dethrone her and really just thinks that Denise is an entitled b***h!"

"Lisa has been the head honcho since the show started and she is appalled to hear that Denise is already barking orders over such things as her trailer and her wardrobe," the insider revealed.

It is not only Lisa that is fuming over Denise's arrival, as co-star Erika Jayne flipped out over Richard's outrageous salary — $1 million for her debut season!

"The girls just think that Denise seems to just really need a paycheck, bad," the source added.

But not all of the housewives are determined to take down Denise!

As previously reported by RadarOnline.com, Kyle Richards, 49 — who has been finding it hard to be friends with Lisa because of her "pettiness" — is determined to form an alliance with the the 47-year-old ex-wife of Charlie Sheen.

"Kylie assured Denise that she's got her back when the bulls**t and cattiness comes her way," a source said previously.