By Peter Bowes
BBC News, Los Angeles
Madonna has kicked off her Confessions world tour with a high-energy performance involving a cross and a giant disco ball.
Madonna: 'Agility and vigour'
Stagehands involved in an industrial dispute picketed the venue in the Los Angeles suburb of Inglewood, but the protest failed to disrupt the concert.
Despite some of the highest ticket prices ever for a pop concert, the gig was a sell-out.
At 47, Madonna performed with the agility and vigour of someone half her age.
The singer emerged from a huge mirror ball that descended from the ceiling at the end of a catwalk section of the stage.
Dressed in S&M style riding gear, complete with whip, Madonna started the show with the song Future Lovers.
In the background, video footage of people falling off horses served as a self-deprecating reminder of the singer's much-publicised riding accident.
It was not long before she belted out the biggest crowd-pleaser of the night, Like a Virgin.
Madonna later suspended herself from a giant mirrored cross while performing the ballad, Live to Tell.
The Confessions tour will be seen in Europe, North America and Japan
Based on the Confessions on a Dancefloor album, fans were treated to a hedonistic mix of full-on dance music and disco.
"I think she's amazing," said Todd Noble, from San Diego.
"I saw her 15 years ago and it's funny to think back, I'm 36 years old and I'm watching the same thing, better or as well as she did then - she's phenomenal."
"We loved it but it wasn't long enough," added Micole Noble.
Other fans were upset that the show appeared to end abruptly and there was no encore.
The lights came up on the auditorium immediately after Madonna finished a medley of Lucky Star and the new single Hung Up.
"Madonna just left without saying bye. I love her but it was kind of sudden," said Bobby, from Los Angeles.
The political imagery that dominated Madonna's Reinvention Tour two years ago was again part of the show.
The singer emerged from a huge disco ball
Images of third world poverty were flashed on the big screen together with messages about AIDS and web site addresses of organizations such as Bill Clinton's Foundation.
Photos of prominent world leaders were also shown.
They included Tony Blair and President Bush, who prompted a groan from the crowd.
The concert took place at the Great Western forum, a vast arena that used to be the home of the Los Angeles Lakers basketball team.
The venue is currently in the grips of an industrial dispute with stagehands locked out from their jobs in a row over pay and working hours.
Seizing the opportunity to air their grievances to a Madonna-sized audience, the union members and their supporters turned out in their hundreds.
"We're picketing the main gates to educate the public as to what it is that the local union is trying to accomplish," said union official Mike Miller.
"This employer is cutting industry standard wages by over 35%."
But the picket lines had no impact on the show with many fans saying they took no notice.
Ticket prices on the US leg of the tour vary according to the venue, but they start as low as $55 (£30) increasing to $375 (£208) for the better seats.
Madonna poked fun at her 2005 riding accident
Over 15 weeks the Material Girl's show is expected to gross in the region of $190 million (£101m).
"It was worth the money," said Brady Kazar who paid $350 for his ticket and travelled to LA from Austin, Texas.
"When I saw the price I was a little taken aback but an icon like Madonna's worth seeing.
"It's worth paying that kind of money for the experience," added, Todd Noble.
The UK leg of the tour starts in Cardiff on 30 July.