Live8, Hyde Park, London

In its own way, Saturday's Live8 concert suggested solutions to a couple of troubling problems. Not just the headline one, regarding the possibility of Making Poverty History, but also the no less pressing one of putting an end to pop-concert longueurs.

By restricting performers to two or three songs apiece, the organisers ensured the show would be a sort of live Greatest Hits compilation, so if you don't like a particular act, there's not long to wait before another comes along to tickle your fancy.

The extraordinary dispatch with which successive acts were shuttled onstage and off speaks volumes for the logistical genius of Harvey Goldsmith, the day's other, more retiring hero; kudos to him and his backstage army.

But dotty diva Mariah Carey's unctuous self-regard; "Bring me water! And a mike-stand! Here's my masseuse! Whaaat? There's no mike-stand?", clashed badly with the agreeable tone sustained by nearly every other performer, and her set effectively deflated the mood they had so assiduously built.

Robbie Williams restored excitement with a brief set that confirmed him as one of the bravura performers of his era, part cheeky chappie, part brash rocker, all entertainer.

It was an event studded with notable moments, some more welcome than others. The Macca/U2 overture of "Sergeant Pepper's Lonely Hearts Club Band" was a brilliant gambit which both recalled the original Live Aid concerts, "20 years ago today", and ensured the show started with a bang. Coldplay's wry insertion of a snatch of Quo's "Rocking All Over The World" into their set hinted at a humour absent from their albums, and their addition of Richard Ashcroft and "Bitter Sweet Symphony" was an early contribution to the day's bulging collection of anthems.

Elton John bestows his patronage upon a different youngster each year - Eminem, The Scissor Sisters, etc - and this year it's Pete Doherty's turn, poor love. Hasn't he suffered enough? Their brief swing through Marc Bolan's "Children Of The Revolution" was less remarkable for its music than for Doherty's outfit, military jacket and peaked cap with Sgt Fury-style stogie and questionable eye make-up.

Dido was introduced by Bill Gates ("one of the world's greatest philanthropists"), which seemed eminently appropriate. If there was anybody onstage today with less charisma than him, it was Dido, whose mild, Bridget Jonesian flutterings induced somnolence before Youssou N'Dour arrived to perk matters up with another anthemic duet, of "Seven Seconds".

REM's uplifting spot, blending the anthemic "Everybody Hurts" with the rousing "Man On The Moon" demonstrated how brilliantly this one-time indie garage band has redefined the essence of large-scale stadium dynamics. By contrast, Ms Dynamite seemed out of her depth, though the version of Marley's "Redemption Song" was welcome. The earnest Keane and engaging Travis were well-received, the latter's falsetto "Stayin' Alive" coming courtesy of Fran Healy's "extra-tight underpants", as was St Geldof, admitting he couldn't resist the temptation to insert "I Don't Like Mondays" into the show.

Elsewhere, Sting played his old Live Aid set cleverly adapted, via back-projections of the G8 leaders, to refocus attention on matters in hand. The heavy hitters turned in fine sets, The Who following Sting in using video images to pointedly redirect "Who Are You" and "Won't Get Fooled Again" at the G8 leaders, McCartney capping proceedings with a chipper, upbeat finale, and Pink Floyd furnishing the day's most hauntingly memorable moments with a typically transcendent set.

But the best performance was Madonna, whose slot featured gospel choir and head-spinning B-Boy dancers, and it was marked by diligent preparation, from her clear, well-coached vocals to the slick band and staging, demonstrating how seriously she took the event.