Katy Perry posed for photos in a sexy Gucci gown as she arrived at the Grammy Awards in LA tonight. Katy didn't bring along boyfriend John Mayer to the red carpet, instead choosing pal Allison Williams as her date. Earlier this week, Allison chatted about her friend Katy, saying, "She's the hottest date. She's a friend of mine, and she's nominated, as she should be." Katy will have plenty of support if she takes home the win for best pop solo performance for "Wide Awake." Even if she's not the winner, Katy will take the stage as a presenter during the show.