In Las Vegas, on August 26, the unbeaten American boxer Floyd Mayweather Jr and the immensely popular Irishman Conor McGregor will face off in a boxing ring, where only striking with hands while standing is allowed. It would be just another boxing match, albeit a huge one, except that McGregor is not even a boxer. Instead, he holds the lightweight and welterweight titles in mixed martial arts (MMA), an emerging combat sport where striking and grappling with both hands and legs is allowed, both while standing and on the ground.