The X Factor UK's third winner, Leona Lewis, joined Alex & Sierra for a slowed down version of her massive hit, "Bleeding Love." Alex & Sierra focused on singing harmonies and let Leona run with the song a bit. Leona had this to say about A&S: "They're so cool and lovely and we were having a blast chatting backstage. They're genuinely lovely people." And that's a genuinely lovely haircut on Alex.