By Ian Youngs
Entertainment reporter, BBC News, Cardiff
The stage show involves 250 crew and £1m of jewellery
Madonna has begun her new world tour in Cardiff, proving to fans that she can still cut it on stage at the age of 50.
In a typically energetic performance, the pop superstar played two hours of hits from her 25-year career.
It featured radically reworked versions of some of her old favourites, such as a techno remix of Like A Prayer and a rock take on Borderline.
"She gets better with age," said Lewis Aldous, 23, from Brentwood, Essex.
He said Madonna looked "incredible", adding: "She looks like she's in her 30s. This is the most fast-paced tour of recent times, especially Like A Prayer."
Maria Paradisis, 32, who travelled from Sydney, Australia, for the show, said Madonna's dancing was "mesmerising".
Excerpts of Madonna's performance and fans' reaction
"She can still shake it like she's a 20-year-old," she said.
But some fans at the Millennium Stadium were not so happy with her latest reinvention.
"She didn't do any of the traditional stuff that everyone loves her for," said Susan Harvey from Cardiff.
"For £85 a ticket, I was really disappointed."
The show is split into four sections - Pimp, Old School, Gypsy and Rave
Danielle Wheeler, 26, said she was "not as good as Kylie", while Stephanie Olokopa, 20, from London, gave the show six out of 10.
"She was late and she didn't even thank the people," she said.
The show was first of 51 dates for the pop superstar, who celebrated her birthday a week ago.
It involved 250 crew, 16 dancers, eight costume changes and £1m of jewellery.
The concert was split into four sections - Pimp, Old School, Gypsy and Rave.
Madonna appeared on a jewel-encrusted black leather throne with the letter M written on its back.
Opening with Candy Store, the first track of her latest album Hard Candy, the Pimp section was characterised by revealing and risque black outfits for Madonna and her troupe.
When a classic white convertible rolled on, it took Madonna and her dancers out into the crowd, with Madonna donning the driver's white top hat before pushing the car back.
The intricately planned visual spectacle was as potent as the music, and Madonna is the master at using colour, costume and choreography to full effect.
She was raised on podium for Vogue with four female dancers wearing long black gloves and boots and very little else.
The set included old and new hits
After that, it was into the Old School segment - intended to evoke her 1980s New York roots - with Madonna appearing in red shorts, pop socks and a skipping rope, surrounded by the kids from Fame.
Into the Groove was the first of her '80s hits to be updated, backed by heavy bass and trance piano.
She then picked up a guitar for Borderline, backed by a more conventional rock band set-up.
The star donned heart-shaped sunglasses for She's Not Me, from her latest album, with her old videos flashing up behind her.
When four dancers appeared as Madonna at various stages of her career, the singer went on to abuse them before indulging in some very frenetic, angry dancing.
With her long, wavy blonde hair, fit physique and endless stamina, she doesn't look too dissimilar to the Madonna of a couple of decades ago.
She certainly doesn't look ready for a Saga subscription.
The Gypsy segment began with Madonna in a black cloak writhing on top of a black piano, before her dancers donned hooded robes for Spanish Lesson.
Madonna changes costume eight times
They then ripped off the cloaks to reveal shiny, gaudy shirts and indulge in some flamenco-style dancing.
Not everything quite made sense - but it looked quite good, and that, you suspect, is what matters to Madonna.
With her dazzling friends, she went on to play a Europop version of La Isla Bonita, complete with big, bearded violinist in a sequined shirt.
The final section was Rave, which started with a pair of sparkly American football shoulder pads for her recent hit 4 Minutes.
It then turned into a full-on rave as the queen of pop played thumping techno versions of Like A Prayer and Ray Of Light.
During Like A Prayer, screens behind her flashed the names of sacred figures from various religions and quotes from holy texts.
Most of the crowd seemed to lap up the pumped-up dance remixes.
But as she strummed guitar in a skin-tight silver top, surrounded by futuristic creatures during Ray of Light, lasers firing over her head, it was tempting to think that maybe she should calm down just a bit.
The entire night had the feel of a giant nightclub - and that is something that some purists didn't like.
But heavy beats made the more mediocre new songs more passable, and the momentum was maintained by non-stop music even when she was off stage.
With wailing thrash metal guitars at end of Hung Up, Madonna posed, hand on hip, seemingly satisfied with her night's work.
Now she's hit 50, she seems even more determined to prove that she doesn't stand still, and she certainly doesn't slow down.
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