Metallica, Wembley Stadium, London <img src="http://www.independent.co.uk/template/ver/gfx/fourstar.gif" alt="fourstar"/>

Halfway through Metallica's set at Wembley Stadium James Hetfield says: "There's a different energy in here than there was yesterday". He's referring to Live Earth that took place the previous evening. While the global warming concert was attended by Genesis, Keane and Metallica fans alike, tonight's crowd is hardcore heavy metal.

There can only be a handful of bands on the planet that command such devotion, affection and fanaticism as Metallica. Remember, these are the notoriously uncompromising guys who went after their own fans for illegal downloads in 2000 and their 2004 rockumentary, Some Kind of Monster, makes Spinal Tap look like Westlife.

Yet the true metal-head forgives all and their fanbase, as is evident by tonight's crowd, spans generations. Even parents are here with their kids. Yes, Metallica are one of those few bands where "huge" doesn't even begin to describe their following.

First up on the bill are prog-metal band Mastodon who manage to sound suitably epic during their half-hour slot. They're followed by thrash veterans Machine Head who win the day through a combination of pummelling riffs, frenzied blast beats and gratuitous swearing. They're good fun, which is more than can be said for HIM. This is snogging music for Goths. But is doesn't matter because Metallica are on soon.

With a show of this scale Metallica can't fail. Before the opener "Creeping Death" is over they have the entire audience going mental and when they unleash "For Whom the Bell Tolls" the mosh pits are so frantic it looks as though the crowd is trying to eat itself. The first verse of "Sad But True" is sung entirely by the fans while "Master of Puppets" is devoured with such rapture that it is awe-inspiring.

You wouldn't think that playing venues even of this size would be a big deal for a band with Metallica's experience, but they seem genuinely moved by the reception they receive tonight. There's a surreal moment as the stadium woah-woahs during "The Memory Remains" with the monitors revealing a close-up of drummer Lars Ulrich's face. He looks dumbstruck.

Tonight is essentially a greatest hits show so the energy rarely falters. Sometimes, as with the cheesy stadium rock of "The Unforgiven" or with the odd bass solo, it's hard to take Metallica seriously. But by the time "Enter Sandman" and the fireworks arrive, everybody's won over. Hetfield tells us "Metallica are alive and well in Wembley Stadium!" and he's right. Wonderful.