Backstreet Boys never thought they would sell out the O2 Arena in the London.

The superstar boyband put on an energetic show at the huge venue on Friday (04.04.14) as part if their worldwide 'In a World Like This' tour.

Addressing the fans, Kevin Richardson said: ''Two years ago [A. J. McLean] mentioned he would rejoin the band and two years later I can't believe we have ... sold out the O2.

''Thank you, you're amazing. It feels good to be back on stage with my brothers tonight.''

The group are on the road celebrating their 20th anniversary, and are happy to be back with their original line-up - completed by Howie Dorough, Nick Carter and Brian Littrell - with Kevin returning to the band two years ago following his departure in 2006.

The 'As Long As You Love Me' hitmakers didn't disappoint, putting on a great show with a hit-filled set including the likes of 'I'll Never Break Your Heart' and 'All I Have To Give'.

The concert also had its share of emotional moments, with the group paying tribute to their families and friends.

As well as Nick kissing a fan during new song 'Permanent Stain', Kevin and A.J. dedicated 'Show 'Em (What You're Made Of)' to their sons.

In another tender moment, the boy band held a moment's silence for their bodyguard Johnny Q, who tragically passed away last year.