Justin Timberlake, Wireless Festival London, review It's Jay Z and JT. Like a black and white, hip hop R'n"B- double act, the US superstars are tag-teaming this year's UK Wireless festival, sharing the headline spots across three nights in London. Former Disney Mouseketeer and boy band star Justin Timberlake topped the opening night, introducing the veteran rapper for encores before Jay Z's Saturday night spot, where Timberlake will be amongst his guests. Then they are both back for a double bill on Sunday. Was there really no one else available? Or are these two versatile and charismatic performers deemed so far ahead of the rest of the field there is not much point in anyone else turning up? On this evidence, it may well be the latter. British acts are, for the most part, low profile at the three-day urban festival, with only Emeli Sandé, Rita Ora and a Calvin Harris DJ set prominent among supports. For all the growing confidence and raised skills levels of UK rap and soul artists over the past decade, the bill at Wireless reminded us that this is still predominantly an American musical genre. What is more interesting is that, on an opening day dedicated to slick, smooth, jazzy nu soul performed by some of the most dynamic and honey-toned black singers in the US, including John Legend, Miguel and Trey Songz, it was the blue-eyed Disney kid who trumped them all. Like other once-in-a-lifetime talents from Elvis to Eminem, JT has become the crossover star of a black genre by mastering all the sounds, styles and moves of the most talented black artists, then adding a very direct, accessible, crowd-pleasing commercial pop wallop of his own. To compete at this level, you don't have to just be good, you have to be extraordinary, and Timberlake sings, plays and dances with dazzling grace and finesse. Where many urban pop acts have reduced their backing bands to a DJ and a laptop computer firing out pre-recorded beats, Timberlake stands up in front of a 15-piece big band featuring horns, percussion and vocalists, reshaping the digital machine grooves into sinuous, old-school funk. The singer really leads from the front, picking up guitars and jamming on keyboards with a playful showmanship that stirs up everyone on stage. This is one smiling, happy, jiving ensemble. That kind of enthusiasm is infectious, radiating out from the stage and enveloping the crowd. To be fair, old gangster rapper Snoop Dogg almost rivalled Timberlake on the opening bill, with a laptop set dependent almost entirely on his sly charisma and popular hits extolling the joys of pimping and dope-smoking. But there was still a tangible gulf between the two. Snoop Dogg is an incredibly engaging pop character. Timberlake is a potential multi-generational world-beater. Having taken a five-year break to diversify into a not particularly satisfying Hollywood acting career, Timberlake has returned to music with real intent. He opened with a trio of his biggest hits, the kind of surefire crowd-pleasers other artists save for encores, all the time demanding "Are we there yet?" As the last notes of Cry Me a River faded, Timberlake surveyed the 40,000-strong moving and swaying mass of young, enthusiastic urban ravers occupying an astroturfed London car park beneath the Olympic stadium, and smiled "I think we're there." There was still another hour to go, and it never let up. Timberlake's principal model is Michael Jackson, although drawing more on Off the Wall funk than his later plastic pop. He made that debt explicit on a free-flowing cover of the Jacksons' Shake Your Body Down (To the Ground) but there was a big shot of Prince's rock-funk-jazz swagger in there, too, and it is no coincidence that many of his band members served time in the New Power Generation. This was a set that didn't really rise or fall - rather it was all about keeping the groove and the crowd moving. The arrival of Jay Z on stage, that most royally confident of rappers in a genre never short of bullish swagger, was a crowning moment, like an endorsement from the godfather of hip hop to a new prince of pop.