Notorious

The Dubliner has achieved more in three years with the UFC than anyone in the 20 year history of the organization. From an unknown prospect to the first man to hold two world titles simultaneously, McGregor's knockout-filled march through the featherweight and lightweight rankings sent shockwaves through the world. But as effortless as McGregor's heroics seem, his journey was far from smooth. Just another teenager trading martial arts techniques with his friends, he chased a pipe dream with little promise of reward. No one guessed he would become the biggest pay-per-view attraction in the world. This is not another tale of an athlete born exceptional and groomed for success. It is about how one young man, through bloody-minded determination and indomitable spirit, changed the whole game.

Jack Slack is the pen name of one of the MMA world's most respected analysts and authors. He has appeared on The Joe Rogan Experience.