Harry Styles flashes his underwear during One Direction gig

Harry Styles was left red-faced after his jeans were pulled down as part of a sneaky prank during One Direction's gig in London on Saturday (06Apr13).

The British hunk was performing a solo during the band's hit What Makes You Beautiful at the O2 Arena when his bandmate Liam Payne yanked his trousers to the floor, leaving Harry Styles standing in his black underwear in front of 20,000 fans.

The 19-year-old star quickly regained his composure as he struggled to pull up his skin-tight denims with one hand, while singing into his microphone with the other.

It is not the first time Harry Styles has been embarrassed onstage - he fell to the floor after he was hit in the groin with a shoe during a concert in Glasgow in February (13).