40 people. ' Next up was Little Mix, who sang Don't Let Go. Talking about why they had chosen to sing that song, Leigh-Anne said: 'When we performed that for the first time, we felt like we came together as a group.' Unbelievable: The girls looked overwhelmed by the comments from the X Factor judges after the performance Mixed emotions: Tulisa couldn't stop smiling after their rendition of the track, while Kelly was reduced to tears Jesy added: 'It was so fun but it still felt powerful at the same time. We are so excited to be given the chance to sing this song again.' And Leigh-Anne said: 'To do it in front of thousands of people at Wembley, the adrenaline is going to make us sing it even better.' Wearing sexy monochrome outfits, the girls burst out of the stage on springboards before going straight into the powerful track. Following their performance, Louis said: 'I'm going to predict Tulisa that this time next year, this is going to be the biggest girl group in the UK by a mile. Girls, amazing, but you need the votes!' Feeling festive? Marcus Collins started the Christmas songs with a rendition of Wham!'s Last Christmas Delighted: Marcus said he thoroughly enjoyed the performance An emotional Kelly said: 'I'm sorry I'm crying but I'm just so happy for y'all because I remember where you started. I love you guys, congratulations.' Gary added: 'I'm so happy tonight that you came back with that song, great