Giuliana Rancic and Kelly Osbourne Credit: Neilson Barnard/Getty Images; Mark Ralston/AFP/Getty Images

Buddy cops no more!

Sources reveal in the new issue of Us Weekly that Giuliana Rancic believes her former friend and Fashion Police co-host Kelly Osbourne didn't have her back after she made controversial on-air remarks about Disney star Zendaya Coleman — and she's still fuming. Says an insider: "Kelly is dead to Giuliana."

After Rancic mused on-air Feb. 23 that Osbourne's friend Zendaya, who wore dreadlocks at the Oscars, "smells like patchouli oil, or maybe weed," the women stopped speaking. One source says that Rancic feels Osbourne, 30 — who tweeted, 'I DO NOT CONDONE RACISM,' and quit the show after the incident — "threw her under the bus."

The feud reignited when Rancic appeared on the Today show April 6 and repeated her claim that a writer scripted the Zendaya remark and blamed her delivery on poor editing. The same day, Osbourne cryptically tweeted, "Liars always get caught.'"The timing of the tweet was no coincidence, says a source: "It was about Giuliana."

Their once-close friendship — "we are like family," Osbourne told Us in 2013 — began to unravel after Fashion Police star Joan Rivers passed away in September. Seeing a void, Rancic "tried too hard to be funny," says an Osbourne pal. Another source agrees Rancic began to grate on her costar: "They didn't see eye to eye on what was funny versus offensive." Get more details on the feud here.