Newly single Reese Witherspoon's style has dramatically changed since her split from husband Ryan Phillippe in October of 2006. The 30-year-old mother of two walked solo down the red carpet at Sunday's 79th annual Academy Awards in a sleek and sexy Nina Ricci gown. Meanwhile, Cameron Diaz, 34, is taking chances with her own look (post Justin Timberlake), opting to hit the red carpet in a retro-inspired Valentino gown.

Which actress has the sexiest single style?