Blake Lively attended the Marquee Nightclub at the Cosmopolitan grand opening in Las Vegas to watch her performance of her new BFF – Florence Welch.

Blake looked casual wearing a simple black shirt paired with metallic blue Isabel Marant Fall 2010 pants.

She accessorized with statement earrings and bracelets completing her look with Christian Louboutin Fastissima 120 velours booties.

You’ll be happy to see both legs and boobs are covered ;)

Florence opted for a gold kaftan style look paired with tights and Christian Louboutin ankle boots.

In other Blake Lively news. Chanel today officially announced Blake as the ambassador for Chanel’s new Mademoiselle handbag line.

The ads will be revealed in publications from April.

Credit: Style.com & WorldRedEye.com