Conor McGregor is officially the cleanest fighter in the history of UFC.While the Irishman is often a controversial figure with his outbursts and antics, he has always maintained that he is a clean fighter, a badge he wears with honour.The Notorious has been tested by USADA (United States Anti-Doping Agency) a staggering 49 times throughout his illustrious career.Jeff Novitzky, the UFC's Vice President of Athlete Health and Performance, took to Twitter to reveal which fighter has been tested the most without failing.McGregor was four ahead of UFC heavyweight champion Daniel Cormier, with Rafael dos Anjos, Holly Holm, Stipe Miocic, Robbie Lawler, Amanda Nunes, Jose Aldo and Tyron Woodley completing the top nine.

Amazingly, 11 of McGregor's tests came in the build-up to his boxing debut bout against Floyd Mayweather.

The fight was one of the most talked about in combat sports history, which probably explains why there was such rigorous drug testing.

Ruslan Magomedov, a friend of Khabib Nurmagomedov, recently received a lifetime ban from the UFC for steroid abuse.

McGregor has been firmly back in the headlines recently - which he usually is - after announcing his apparent 'retirement' from UFC on Twitter.

However, just a few days later, after some heated spats with rival Khabib, McGregor announced he will be back in the Octagon soon.

McGregor wrote: "I want to move forward, with my fans of all faiths and all backgrounds. All faiths challenge us to be our best selves. It is one world and one for all ❤️. Now see you in the Octagon."

It seems inevitable that McGregor will partake in a rematch with Khabib in the near future, with the Russian beating the Notorious in Las Vegas back in October.

The rivalry between the pair has got way out of hand, with unforgivable insults exchange between the pair on Twitter of late.