(Cover) - EN Showbiz - Beyonc Knowles has been working hard to ensure her performance at Glastonbury music festival is "perfect".

The American singer has been spending up to ten hours a day rehearsing for her live set at the world famous music event, which takes place this weekend. Beyonc is determined to thrill the crowd with her catalogue of hit songs and impressive dance moves.

"She's been grafting hard," a source told British newspaper The Sun. "She wants her and her dancers' routines to be perfect and doesn't want to get a foot wrong.

"By tomorrow she won't be doing any more rehearsing. She'll be relaxing with Jay-Z and they'll head to Glastonbury together."

Beyonc is following in her rapper husband Jay-Z's footsteps by performing at Glastonbury. He was added to the bill for the 2008 festival.

Other acts taking to the stage at this year's event include British rockers Coldplay, who will be showcasing material from their new as-yet untitled fifth studio album.

Irish rockers U2 are also headlining at Glastonbury this year, after being forced to pull out in 2010 when Bono had to undergo an emergency operation. (C) Cover Media