David Haye taught Justin Bieber how to box.
The former world heavyweight champion encouraged the 'Sorry' hitmaker to take part in a training session at his Hayemaker gym in London, which has since closed down, five years ago in order to teach him how to throw a left hook and a vicious jab.
Speaking as part of Vauxhall's 'Great British Legends' series, he explained: "I did a TV show where I had Justin Bieber on it. He was cool, he was young. It was a while back. It was about five years ago. I brought him down to my gym and gave him a training session. I interviewed him whilst training."
And the 35-year-old professional boxer's tips and tricks obviously stuck with the handsome pop star as he took on his friend Floyd 'Money' Mayweather Jnr two years ago in Las Vegas.
The 22-year-old singer stripped down to his white basketball shorts as he lunged at the 39-year-old retired boxing legend, who was holding hand pads as part of a training session.
The pair have been friends for a good few years and Justin - who has earned himself the nickname 'Moneybags' by the athlete - even walked to the ring with Floyd ahead of his super-fight against Manny Pacquiao last May.
However, 50 Cent - whose real name is Curtis James Jackson III - believes Floyd is only friends with Justin because his daughters Iyanna, 16, and Jirah, 12, are "huge fans" of Justin.
He said previously: "Really, it's about Iyanna. His youngest daughter's such a huge Justin Bieber fan."
Vauxhall's 'Great British Legends' series takes celebrities back to their roots, looks at their early influences and aims to find what makes a 'Great British Legend'.
The campaign celebrates the iconic Astra being a fixture on our roads for over 35 years and it being crowned 'European Car of the Year 2015', making it a true legend of British car manufacturing.