Looks like Ashley Olsen is in love — and the normally very private starlet is making it very public.

Olsen, 22, flew into Las Vegas earlier this week to spend some serious time with her new flame, Justin Bartha, while he films “The Hangover” alongside Bradley Cooper.

Even though the sassy blonde caught the attention of numerous male onlookers in her skin-tight jeans and white blouse, this twin apparently only had eyes for one guy.

After a romantic dinner of sashimi and soup at Stack Restaurant & Bar, Pop Tarts spies spotted Olsen and Bartha partying up a storm with friends until the early hours at the Mirage’s JET nightclub.

We’re told the former “Full House” star seemed really happy as she stayed glued to Bartha throughout the entire evening, dancing and doing shots of tequila.

But according to another eyewitness, the Tinseltown twosome looked as though they should have “gotten a room” on Tuesday night.

After watching “Jersey Boys,” the couple made their way to the Bellagio’s swanky new Yellowtail Sushi Restaurant & Bar, where they apparently “couldn’t keep their hands off each other” as they downed lots of sake and sushi. (Hey, at least we know that Olsen eats!)

“They were rubbing each other, hand-touching and there was barely a break in their conversation," said an insider, adding that nobody in the restaurant even recognized Ashley as her face was almost always preoccupied with more, er, important things. …

“It’s pretty serious,” an Olsen pal told Pop Tarts. “Ashley is really comfortable with Justin. It’s a good fit.”

While Ash was busy busting the moves with Bartha, twin sis Mary-Kate was spotted touching down in Milan, Italy, on Wednesday with a mystery man.

Click here for a pic.

Mother Confronts Ashley Tisdale in Restaurant, Demands She Share Salad

Every star has a story to tell when it comes to a crazy fan, but Ashley Tisdale was left speechless while dining recently with her family in a restaurant in Valencia, Calif.

“A bunch of little girls came over and I thought they wanted an autograph, which was totally cool,” Tisdale told Pop Tarts. But instead, the “High School Musical” sensation found herself confronted by the mother demanding that she give her daughter a bite of salad.

“She wasn’t joking and she wouldn’t go away when I said no,” Ashley added. “It was so odd that a grown woman would do that, especially in front of her kids. It was so wrong.”

And it seems as though the tween idol is attempting to sex up her image a little with her second album, insisting it is far more “grown up."

Meanwhile, Pop Tarts spies spotted the starlet in Vegas last weekend. We're told Ashley was hosting her sister's swanky bash at the Bellagio's The Bank nightclub, but only stayed a few minutes before sneaking out hand-in-hand with her beau. ...

Speaking of Disney dames and their love interests, a Van Nuys airport insider spotted Selena Gomez acting all giddy and excited last week while engaged in an online Windows chat with rumored squeeze Nick Jonas. We're told that there is "no doubt" that those two are together.

Matthew McConaughey's Water Baby

Matthew McConaughey loves to surf — and it looks like his 2-month-old son Levi is already taking after his dad.

“My son loves the shower,” McConaughey told Pop Tarts. “We’ve been to the beach a few times, but he’s already spent a good nine months in 'the water' so he’s comfortable.”

Matthew put his own love of liquid to good use last week and competed alongside Jennifer Lopez in the annual Malibu Triathlon to raise funds for the Los Angeles Children's Hospital.

According to a McConaughey pal, the actor became "obsessed" with athletics after watching too much of the Beijing Olympics.

"One minute he wanted to host a swimming comp at his house," the insider said. "Next thing he was talking about running marathons."

Britney Selling Her House?

A few months ago, a court granted permission to Britney Spears’ father Jamie (the co-conservator of her wealth and assets) to sell her beloved Studio City mansion.

According to the L.A. Times, the pop princess’s posh pad (complete with pool, spa, library, den and three garages) is going for a cool $7.9 million. Pop Tarts has been told that Jamie wants Britney to buy a place in Calabasas, Calif., so she is further away from the troubles of Tinseltown.

Speaking of Spears, Simon Cowell confirmed to "Extra!" that the songstress will perform on his hit British show "The X Factor," which gave Leona Lewis her start in the music biz.

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