Picture - Glee and Dianna Agron

"I was rehearsing for our Wembley Stadium show in London and we had a rehearsal space booked in this warehouse... in L.A. and I am literally singing Trouble... and Usher just walks in and he's like, 'We're shooting The Voice over there and my girl is doing your song'. It's a million to one... and I was just like, 'I don't have hair and makeup or anything but I'll do it'." Taylor Swift on her recent big surprise on The Voice in America, when she turned up unannounced as reality Tv sensation Michelle Chamuel was prepping for her performance of the country singer's tune Trouble.