Tia Carrere's dance moves didn't do her any good last night when she encountered a purse thief in her Las Vegas dressing room following a performance of "Dancing With the Stars: Live in Las Vegas" last night ... TMZ has learned. 

According to our sources, Carrere came face-to-face with a guy lurking in her private dressing room after her 10:00 PM show at the Tropicana last night. Rather than scream for help, Carrere tried to give the guy the benefit of the doubt and see what he was doing there ... but he promptly bolted right past her. 

Carrere then called out for help, but it was too late ... our sources say the guy made off with her purse, two iPhones, and a wad of cash. We're told another dancer, Anya Garris, had her wallet cleaned out as well.  

Carrere called police and filed a theft report. The case is now under investigation.

Maksim and Valentin Chmerkovskiy are used to squeezing into tight spots (cough, leotards) -- but after watching their hysterical attempt at moving furniture ... they should stick to ballroom. 

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"Dancing with the Stars" pro Maksim Chmerkovskiy -- who was with Melissa Gilbert when she hit her head on the show yesterday -- is strongly insinuating ... "Dancing" producers conspired to overstate the actress' injuries to drum up ratings.

"Dancing" host Tom Bergeron announced at the end of yesterday's show -- Melissa had injured herself during her and Maks' Paso Doble routine (below) ... and was rushed to a nearby hospital.



Melissa later announced on her Twitter she had sustained whiplash and a mild concussion during the performance -- but Maks tells us a different story ... insisting the actress just "bumped her head."

We asked if "Dancing" producers tend to play up celebrity injuries on the show for ratings -- and Maks responded ... they don't fake it ... but they "amplify it a little bit."

Mark Ballas and his girlfriend got in a 6 minute, alcohol-fueled fight over Mark's unforgivable sin -- smoking a cigarette after promising to quit.

The altercation flared up outside Playhouse nightclub in Hollywood just after midnight Tuesday.  We're told Tiffany Dunn was outraged that Mark had broken a deal they had -- she agreed to sell her scooter after injuring herself in an accident, and in return he agreed to quit smoking.  But one of Tiffany's friends caught Mark inhaling, blabbed to her and fireworks erupted.

Tiffany screams mid-argument, "You're such a d**k when you drink." For his part, Mark tells Tiff, "You can cry me a river for all I care, and you can swim in it."

Mark tells Tiffany, "You punched me in face 3 times today." She responds, "I was dancing."

Tiffany thinks Mark's fibbing about smoking is a gateway lie: "It makes me wonder what else you lie about. Yeah, exactly, exactly, exactly, what else have you lied to me about?"

At one point ... Mark yanks Tiffany's key chain from her, removes his house key and then hands the chain back. She pushes him and he leaves.

We're told Mark and Tiffany were "hammered," but all ended well. They got a cab together and went home.

Young love.

Mark Ballas tells TMZ ... he was NOT the target of a Jaleel White meltdown during a "Dancing with the Stars" rehearsal session last week ... despite reports to the contrary.

Mark was leaving Hyde in L.A. last night (the same one Paris, Lindsay and Britney used to party at back in the day) ... when we asked about Jaleel's alleged meltdown ... in which he reportedly screamed at his partner Kym Johnson before going off on Mark.

But Ballas says the whole thing is a "complete fabrication" ... telling us, "We're in L.A. man ... everything's fabricated."

Gladys Knight is pulling double duty ... 'cause in between training sessions for "Dancing with the Stars," TMZ has learned Knight is also working on a top secret scripted TV show.

Sources close to production tell us ... Knight has been cast to star in a show called "The First Family" ... about a fictional President of the United States who's juggling work with his family life. We're told Gladys is playing the President's mother.

Sources connected to Gladys tell TMZ ... the Motown legend is working extremely hard to handle both gigs ... and producers on both shows are being very flexible to accommodate the star.

We're told the sitcom is already garnering interest from a major network ... which has made it clear they want to rush production to capitalize on Knight's "Dancing" momentum.

We spoke with Byron Allen -- the Executive Producer of "First Family" -- who tells us, "Gladys is truly an American treasure and we're excited to work with her."

Four-time Pro Bowler and children's author Donald Driver isn't taking "Dancing with the Stars" lightly -- sources tell TMZ, the Green Bay wide receiver is working himself to the BONE to crush the competition.

According to sources, Donald's been working non-stop -- practicing with his partner for 5 hours at a time ... then going home and studying dance moves on YouTube.

We're told Donald pays especially close attention to the male pros -- intently studying their moves and their footwork ... just like a football player would study tapes of old games.

According to sources, Donald's goal is to dance at the pro level -- not just the "celebrity" level.

We're told Donald is so focused on being at the top of his game -- he's even keeping his pro partner Peta Murgatroyd on a strict diet.

As one "Dancing" source put it ... "Donald's work ethic is INSANE!"

Gavin Degraw is up for some serious double duty -- he's joining the cast of "Dancing With the Stars" ... but TMZ has learned he will also continue his current U.S. tour.

Multiple "DWTS" sources confirm the "Not Over You" singer has signed on for the new season -- the full cast will be announced on Tuesday morning.

Degraw's taking on a major work load -- the show premieres on March 19th ... but his tour continues through mid April.

We're told Gavin's dancing pro will most likely join him on tour so they can keep practicing -- but none of his tour dates conflict with 'DWTS' airdates.

As TMZ first reported ... Jack Wagner, Sherri Shepherd, and Melissa Gilbert will also compete for the mirrored ball.

"Dancing with the Stars" pro Mark Ballas has a MAJOR problem with the "Dance Moms" reality show -- telling TMZ, the angry screaming dance coach is verbally abusing the kids ... and she doesn't know jack squat about dancing.

In case you haven't seen the show ... dance company owner Abby Lee Miller has become famous for berating the children ... once telling a crying little girl, "You save those tears for your pillow, in your room, alone."



Mark tells us, "She's not dancing, she's just yelling at them" ... adding, "I just don't think it's the correct way to teach somebody ... Those kids are 6 years old. They're learning. They're babies ... They need to be treated the correct way."

Ballas adds, "Those kids should not be afraid to go to dance."

TMZ has learned the identity of yet another of the contestants for the upcoming season of "Dancing With the Stars" ... the super hot Maria Menounos.

We revealed three cast members yesterday ... "View" host Sherri Sherpherd, "Little House of the Prairie" star Melissa Gilbert, and "Melrose Place" hunk Jack Wagner.

Now we've learned the show has picked the younger and sexier Menounos to join the mix.

People who host "Extra" have a good track record on the show ... Mario Lopez finished second in season three of "DWTS."

Despite rumors he's quitting ... TMZ has learned, "Dancing with the Stars" pro Maksim Chmerkovskiy is COMING BACK TO THE SHOW -- and we got the video to prove it!!!

Maksim touched down in LAX yesterday for his first practice -- he didn't say much ... but as soon as he landed, guy made a beeline for an L.A. dance studio ... where he met with Melissa Gilbert -- one of the stars on the upcoming season.

TMZ broke the story ... Sherri Shepherd and Heather Locklear's ex Jack Wagner are also set to compete on the show.

Season 14 is scheduled to kick off next month.