Prince brought the 'Fierce' out in Beyonce

Prince brought Beyonce Knowles' sassy alter-ego Sasha Fierce to the forefront when the pop diva performed with him at the 2004 Grammy Awards.

The 'Survivor' singer's family and friends insist Beyonce has always taken on a totally different persona when she gets on stage, but it took Prince to make her realise she 'trances out' and becomes Fierce during big shows.