The Roots, Hammersmith Apollo, London

Few groups have the musical courage of The Roots. Philadelphia's favourite hip-hop sons approach a genre overrun with blandness and imitation, with the intelligence and precision of a mathematician, combined with an alchemist's passion for experimentation. What other group, regardless of genre, would not only employ a full-time sousaphone player but start their show with a solo from him? It's hard to imagine anyone else having the nerve, much less the talent, to make it work.

Fortunately for everyone inside the Hammersmith Apollo, the group who began life in 1987 as The Square Roots have both in abundance. It's apt that their name has changed since then: if there's one thing tonight's show isn't, it's square.

Led by the irrepressible Black Thought's rhymes and grounded by the metronomic drumming of ?uestlove – the group's founders and sole remnants of the original lineup – The Roots mix half-a-dozen genres into a single cohesive sound. One of few hip-hop groups who play all their own instruments, their musical timing is second to none. Opener to closer, every track is a toe-tapper, filled with an innate funkiness.

"Here I Come" is especially fearsome, its heavy drum beat complimented by Black Thought's throaty vocals, which pack as much power as a heavyweight uppercut. Its immediacy and impact are staggering, able to turn a diverse, mellow crowd of knowing aficionados into a swaying mob of singalong vocals and fist pumps in seconds.

Equally impressive is the group's ability to take popular tracks – "Criminal", "The Seed 2.0", "Break You Off" – and mould them into entirely new creations, familiar in melody but not in delivery. Even more striking is the audience's reaction to such shifts: appreciating, rather than bemoaning, changes to their favourite songs.

The set nudges two hours, during which time the music never stops, one song running into the next without a mis-step or a slip-up to be heard. Questlove and percussionist F. Knuckles rattle off a stunning five-minute drum solo that eschews showiness for the tightest groove and most effortless feel this side of a Stax record.

The fact that none of this feels artificial or forced is a fitting testament to the indisputable magic The Roots create on stage.