Sienna Miller hosted the grand opening of Esquire House LA this weekend.

The British actress does a complete 180 by going from looking ridiculous in an oversized Matthew Williamson gown, to divine wearing a Nina Ricci Fall 2010 dress.

The strapless elegant tiered dress with a peplum at the waist had touches of lace with the hem falling just below the knee.

Grey Stella McCartney pumps and sleek straight shiny blonde hair completed her look.

Credit: Style.com & Getty