Oscar-nominated actress Keira Knightley is thrilled Sienna Miller will be her on-screen lover in her new movie, declaring she "wishes" she was the Factory Girl star. Miller has replaced Lindsay Lohan in the part of Caitlin MACNamara, who cheated on her Welsh poet husband Dylan Thomas with Knightley's character Vera Phillips in forthcoming John Maybury movie The Best Time Of Our Lives. Knightley is looking forward to getting to know Miller properly and hopes Jude Law's ex-fiancee will give her lessons in being the perfect party guest. She says, "I wish I was Sienna Miller. I watch that girl and she's just fabulous. "She talks to everyone and laughs and smiles and looks as if she is genuinely enjoying herself. "When I talk to her, I hope a bit of her party personality will rub off on me, but it never does. She could give master classes in being the most amazing party guest."