There's little as sad as seeing Muhammed Ali shaking and juddering, a quivering shadow of what was once the nosebleed peak of physical perfection. Seeing him juxtaposed with his glorious past accentuates the tragedy: alone, he's just an old man who still has his dignity, but slapped gracelessly across sports news packages alongside dream visions of the history he made, the shock is amplified. He went from that to this? Jesus. But let's remember him how he used to be, yeah?

And so, Madonna: a doddering, obsolete goat who hasn't been cursed with illness like the former Cassius Clay but who wrote herself out of contention by releasing some of the worst music humanity ever heard. Celebration only highlights this fact: released so Madge can escape from her Warner Bros contract, this third greatest hits collection is the perfect document of what happens when genius, intelligence and inspiration fade away to be replaced with sad desperation and the echoing nausea of Mammon-like cash-hunting. It feels even more obsolete when you consider the outright brilliance of The Immaculate Collection, which remains the definitive, cast-iron best-of, and which was released almost two decades ago

And it's not a case of only wanting to concentrate on the early material — the 'Holiday's, the 'Like A Prayer's, or the still-sleazy 'Justify My Love's. Because Celebration is bafflingly non-chronological, which means 'Vogue' is stranded between the execrable 'Music' and '4 Minutes'. There's a run of quality that takes in 'Holiday', 'Like A Virgin' and 'Into The Groove', but it feels like you're listening to some cretinous local radio DJ rattling out whatever Madonna hitz he can find without a thought spared for pacing or indeed coherence.

The closing run on the second disc: let's just say, dear reader, that The Hague's war crimes court has been convened for much, much less. 'Die Another Day', 'Don't Tell Me', 'Beautiful Stranger', the new Oakenfold-produced title track . . . at times like this, one wants to wear a black, single-cup cone bra in memory of the pop star that once was. And 'Revolver', which closes the first disc and features the dubious gurgling of Lil Wayne, is an abomination, a stillbirth, a slap in the face of God. Over the top? Go on, put it on. I defy you not to burst into tears before the first chorus.

Put simply, 'La Isla Bonita', 'Material Girl' and the rest of her canon (because her early work really does suit the term, not only because of the quality of the tunes but because of the legend they helped carve for Madonna) are untouchable, and still contain as much fizz and bite as ever. They were also almost all on The Immaculate Collection. And everything she's released since? The overly sexualised material has not aged well. 'Erotica' feels like a museum curio now, brought into sharp relief by the staggering sight of her "suggestively" licking her wrestler-style wrist bandage on the sleeve of Hard Candy to prove the ferocity of her sex. Whatever happened to her clever, cheeky subversiveness? Where once she caressed and bucked and writhed, forever winking at the lens, erotica has since been superceded by bland, garish pornography. And the rest is bandwagon-jumping pseudo-future pop: 'Frozen', granted, is strong, but leaving off 'Drowned World/Substitute For Love' in favour of 'Miles Away'? Seriously?

Please, don't buy this. The Queen is dead.