Nicole Richie & Hilary Duff: Showdown at the Chateau Marmont

Nicole Richie and Joel Madden were spotted dinging at the Chateau Marmont in LA and they looked like "they were in their own lover’s world," a witness told In Touch Weekly.  But te mag divulges that there may have been a more serious reason why Nicole was keeping a close eye on Joel on July 9.  Just a few tables over, his ex-girlfriend Hilary Duff was sitting with her sister, Haylie, and a group of friends.  Although they were in the same place, "there was no greeting, no acknowledgement," the spy claims.

Nicole Richie & Hilary Duff: Showdown at the Chateau Marmont

Showdown at the Marmont?  Hilary, 19, and Nicole, 25, have never been friends and tensions rose when Joel, 28, started dating Nicole just weeks after he and Hilary broke off their two-and -a-half year relationship. 

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The story reports that though Hilary kept quiet at first but now, she’s lashing out.  First, she labeled Joel and Nicole’s relationship a “rebound” and said in the August issue of Seventeen that she “felt disrespected that he moved on so quickly.”  Then in the new issue of Hollywood Life, she take a jab at his new high-profile lifestyle with Nicole, saying that when she was with Joel, “It would’ve been cheesy to be a couple that just loves to go our and get photographed.  So you do wonder why they do it now when they were so against it before?”

Although Nicole has Joel (and is having his baby), an insider says that The Simple Life star dislikes Hilary for other reasons.  “Nicole used to hate it when Joel talked to Hilary and got really jealous,” says another pal. 

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Plus, Hilary - who’s been looking sexier than ever after a recent weight loss - is a “mogul,” explains the friend.  “Hilary has five businesses and tours around the world.  Nicole is just an ex-reality star.  She wants to be taken seriously, not just be known for doing nothing.”