Science of Speech, Hammersmith Apollo, London

When this show was announced in February, it looked like New York hip-hop was making a stand against today's questionable customisation of the genre or someone had worked out a way to neatly cash in on the legendary reputations of two groups and an MC who've each carved a credible niche in music history. Rakim, for instance, has been every rapper's favourite rapper for the last 25 years, responsible for inspiring lyricists to move beyond pre-school wordplay in favour of more complex rhyme schemes and metaphors. Tonight, he's a respectful warm-up performer, cooly reeling off classics like "Paid in Full" and "Don't Sweat the Technique" with just the help of a DJ. It feels a little rushed and if he'd had 20 more minutes, he might have converted some of the youngsters in the crowd who couldn't help but look on at the 43-year-old obliviously.

De La Soul, on the other hand, pull off a mind-blowing set, packed with energetic camaraderie, classic hits ("Stakes Is High", "Me Myself and I", "Buddy") and even disses to the bored-looking photographers and females on the front row who'd merely come out to gawk at Hollywood crossover star Mos Def later, as pointed out by group member Posdnuos, who mocks with a smile. At one point, it wouldn't have even mattered if the headliners failed to show up, because the trio set the bar so high, Black Star's eventual appearance on stage is uncomfortably anti-climatic. The duo – made up of Def and his lesser known, albeit respected compadre Talib Kweli – only ever released a single album in 1998, and despite appearing on each other's solo efforts from time to time, their outing tonight initially lacks chemistry and is annoyingly low-key. They deliver a lengthy retro-themed set, made up of an awkward assortment of Black Star songs and their individual solo hits – but it seems the all-dancing, all-singing, charismatic Mos Def is given more of the spotlight, with the more modest Talib playing the dutiful sidekick.

There's a random appearance of rapper Jay Electronica at one point, who sort of livens things up during a performance of "Just Begun" and for the rest of the night, Black Star ignite a few sparks that indicate they might have made for an exciting duo had they not quickly gone their separate ways before the dawn of the new millennium. But the award for the best performance on the night undoubtedly goes out to De La Soul.