Lady GaGa has delighted fans by diving into the crowd at a festival this weekend.

The 'Alejandro' hitmaker - who was performing at the Lollapalooza festival in Chicago - launched herself into the audience wearing see-through fishnet underwear while her friends Semi Precious Weapons performed their set on Friday (06.08.10).

Lead singer Justin Tranter said: "She stood on the side of the stage, and then during the song 'Magnetic Baby' she started playing drums with Dan Crean. Then she started singing back-up vocals, then she and I made out.

"Then she stage-dived and I joined her while she stage-dove. And then we made out while stage diving. And then she left. She used to get on stage with us all the time, but since she's so famous, normally it's not safe for her. But she played the same stage we played three years ago, and I think she was so excited about us playing that stage."

Later in the day, Gaga took to the stage for her headlining slot, three years after her first appearance playing to a sparse crowd in an afternoon slot.

Taking to the stage this time around, she told the masses of fans: "My name is Lady Gaga. I thank you for coming to my show. I didn't used to be brave. In fact I wasn't very brave at all.

"But you have made me brave, little monsters. So now I'm going to brave for you. Tonight, I want you to free yourself."

Other acts to have performed at the world-famous three-day US music event this weekend included Arcade Fire, Soundgarden, Green Day, The Strokes and Erykah Badu.