Lady Gaga shocked fans everywhere on The Voice finale when she brought out judge Christina Aguilera for her performance of 'Do What U Want', replacing R. Kelly. It was one of the most epic nights in music of 2013, and with the fans' reactions Gaga decided to ring in the new year with a bang. Today Gaga released a re-worked version of the song that features none other than Legendtina. And basically it's just as flawless as you would expect. Christina's vocals blend effortlessly with Gaga's, raising the chorus to unattainable heights, and of course during the bridge and final chorus Gaga and Xtina engage in a battle of runs as they each try to outdo the other. It's one of the best duets as two of the world's finest pop divas team up and show everyone who's boss.