Madonna is holding "brutal" rehearsals for her Super Bowl show.
The star is to perform her new single 'Give Me all Your Luvin' live for the first time at the NFL Super Bowl XLVI Half Time Show on Sunday (05.02.12), and has been putting Nicki Minaj and M.I.A. - who appear on the track - through their paces in preparation.
A source told The Sun newspaper: "Madonna has been brutal in rehearsals. Although they've been having a laugh, they've been doing up to 12 hours in a New York studio.
"She's saying they can sleep after the Super Bowl. She's involved in every aspect of the show, including Nicki and M.I.A's outfits.
"Nicki has been telling pals it's the most gruelling thing she has ever done and wouldn't expect anything else, calling it an 'epic learning experience'."
Despite the gruelling rehearsals, M.I.A is looking forward to appearing on the show, one of the most watched programmes of the year in the US.
She told BBC Radio 1: "I've never been to the Super Bowl, so it's my first time. I'm going to be performing with Madonna and Nicki Minaj. If you're gonna go to the Super Bowl, you might as well go there with America's biggest female icons."
Madonna's performance will be broadcast live from the Lucas Oil Stadium, Indianapolis on Sunday.
Other performers to have previously appeared at the Super Bowl include The Black Eyed Peas, Sir Paul McCartney and Bruce Springsteen.