Travie McCoy’s road to this sold-out show at the O2 Academy is a fairly unusual one for a hip hop superstar in waiting. As frontman of the Gym Class Heroes, he wasn’t discovered by P Diddy or Jay-Z, but by Fall Out Boy bassist Pete Wentz as one of the first signings for his record label Decaydance and rapped about Myspace and finding true love, rather than guns and girls. However, to forge his solo career, McCoy has chosen a topic for his first release that’s much more familiar for most rappers — wanting to be filthy rich on debut single Billionaire.

McCoy’s partner on that track, Bruno Mars opens the show tonight. This is pretty brave of McCoy as Mars has just had his own number one hit with Just the Way You Are and the muted claps that usually greet a support act are replaced with hysterical screams.

Mars in unflapped, though, and delivers a set full of poppy soul with echoes of early Michael Jackson, vintage Marvin Gaye and Seal. At once charismatic and bashful, Mars leaves the stage to rapturous applause and seems to be making damn sure he’ll be too big to play places this size when he’s top of the bill.

Most would struggle to follow at a set as well received as that, but when Travie McCoy nonchalantly strolls out half an hour later, he ends any possibility of a let down. Backed by a full band, he motors through his debut album Lazarus, most of it is in the same summery, well-adjusted vein as the Gym Class Heroes. Particularly good are Need You and We’d Be Alright, which samples local heroes Supergrass. Predictably, when Mars comes back out to do Billionaire, the screaming reaches a whole new register, but it’s just one of a clutch of great tracks in the set. Arenas beckon for both of them.