London: Singing sensation Justin Bieber had an impromptu boxing session with British champion David Haye.

The 'Baby' hitmaker stepped into the ring with the current World Heavyweight Champion at his training gym in London on Sunday.

Haye in his Twitter post admitted that he was impressed with his 17-year-old opponent's punching skills. He said, "Great workout in The Hayemaker Boxing Gym, Justin Bieber. You sure can pack punch!! I'm now a Belieber! Stay Blessed!"

It's not the first time the boxing giant has taken on a pop heavyweight - he sparred with rapper Dizzee Rascal earlier this year.