J.Lo's Quick-Change in Vegas Pays Off!

Just back from their Mexican getaway, Jennifer Lopez and her ex, Casper Smart, were spotted at Hakkasan Las Vegas Restaurant and Nightclub at MGM Grand last night. At dinner, J.Lo looked stunning in a vintage white jumper and Valentino leopard-print bag

[Credit: Denise Truscello/WireImage]

Before enjoying the rest of the night, she did a quick change into a long-sleeved black crop top, leggings and sneakers.

[Credit: Denise Truscello/WireImage]

Forty-five never looked so fabulous!