When news broke that Robert Pattinson moved on from Kristen Stewart with a new girlfriend, you knew that mystery brunette's identity wouldn't be a mystery for long. So who's the lucky lady?

Her name is Sydney Liebes. The pretty personal trainer met Pattinson on the set of 'Mission: Blacklist,' where she was enlisted to whip him into shape for his role.

"This is kind of her first big A-list client," one of Liebe's pals revealed. "She's trained clients at Equinox Beverly Hills but nothing of Rob’s status. So she started training him and they were connecting really well," the source added. "Rob invited her out."

Don't think Liebes is just trying to use Pattinson for his name and attention, though. Her bud noted, "I don't think she's seeking celebrity status. We're into the whole Hollywood scene, so she easily could have done that a long time ago," a friend pointed out. "She's a good girl. She's really down to earth and low-key. She’s excited about Rob, but at the same time she’s keeping it really quiet."

Indeed, when Radar Online asked Liebes for a comment on her relationship with Pattinson, she politely declined to talk about it.

That's one thing Stewart and Liebes have in common ... but it pretty much ends there. Another source dished, "Sydney kind of looks like Kristen, but she's not at all like her. She's down to earth, really energetic, uplifting, whereas Kristen is so somber and tomboyish." Ouch! The source added, "Sydney's a great match for Rob!"

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