IN THE STREETS & ON THE WEB

LMAO! CHRIS BROWN & RIHANNA HAVE A DANCE OFF IN THE CLUB!

According To GateCrasher: Chris Brown spent the first half of Monday night with his current girlfriend — and the second half with his ex.

The controversial R&B artist launched his first art show — a collaboration with pop artist Ron English called “Dum English” — at Opera Gallery in SoHo, and a herd of industry pals came out to support the budding Picasso. Along with DJ Khaled , Busta Rhymes, actress Tika Sumpter and stylist June Ambrose, Brown’s girlfriend, petite model Karrueche Tran, was also at the gallery all evening.

A source at the event says Tran stayed by the 23-year-old Brown’s side for much of that time and the two shared “multiple embraces.” At one point, Brown smiled while plying the biracial beauty with a glass of Champagne. They swayed together to music played by DJ M.O.S. and Tran hung on Brown’s every word as he told guests about his artwork, which includes a piece entitled “Hell-no Kitty” — his homage to the Hello Kitty character.

The couple didn’t stick together the entire evening, however. According to a second source, Brown showed up at Avenue nightclub in Chelsea around 1:30 a.m. with “a bunch of friends [and\] a couple of girls,” although Tran wasn’t one of them.

About 45 minutes later, Brown’s ex-girlfriend Rihanna entered the same club “with her large posse of socialites,” including comedian Aziz Ansari . The source says the singer-turned-actress, who recently appeared in the flick “Battleship,” was dressed in a pinup-style white dress, black sunglasses and Converse sneakers. The Barbadian beauty’s group took a table directly across from Brown’s entourage.

That’s when things got interesting. Our source said Brown could be seen “admiring Rihanna from his table across” the room. Her beauty apparently made him thirsty, because he “started the party with shots of Patron” tequila and Ace of Spades Champagne.

Soon after that, a second source tells us RiRi and company started dancing on top of the banquettes.

As if on cue, those in Brown’s party did the same, directly facing Rihanna’s group, in a dance-off.

Despite the “You Got Served”-style theatrics, our sources say neither Brown nor Rihanna approached each other or had any kind of face-to-face interaction.

Brown was the first to call it a night at 3:30 a.m. Rihanna left closer to 4.

The former couple have crossed paths more than once over the past couple weeks — at nightclubs SL, 40/40 and now Avenue — but when it comes to the public eye, Brown seems to be sending the message that he’s in a relationship with Tran for the time being.