Ali Fedotowsky didn't get lucky in Las Vegas.

While in Sin City for the June 3 Miss USA pageant, the former Bachelorette, 27, flirted with fellow judge Rob Kardashian -- but got the cold shoulder.

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"Ali's goal all weekend was to hook up with Rob, and she kept telling friends it would happen," a source tells Us Weekly.

While her rep says "this is completely untrue," the insider says Kardashian, 25, -- who has been dating British pop star Rita Ora, 21, since December 2011 -- "never showed interest in Ali."

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Fedotowsky and Roberto Martinez called off their engagement in November 2011 after falling in love on season 6 of The Bachelorette in May 2010.

Now, Martinez, 29, is in talks to return to the franchise and be the Season 17 Bachelor."He wants a deal near what Emily [Maynard] asked for, around $750,000," an ABC source tells Us of the San Diego insurance agent. "But the network will give him pretty much anything."

VIDEO: Ali "freaking out" over Roberto's potential Bachelor casting

But Fedotowsky is hoping her ex won't appear on the show. "Ali is dying for him not to do it," says the source. "She feels it's a slap in the face."

This article originally appeared on Ali Fedotowsky Hit on Rob Kardashian in Sin City!