Photos by Getty Images Terence Crawford should fight Conor McGregor using mixed martial arts (MMA) rules, Crawford's promoter Bob Arum said. Arum previously put forward a two-fight proposal on ESPN which would see Crawford and McGregor compete in the UFC, before engaging in a boxing rules rematch. Speaking to Business Insider this week, Arum reiterated his idea and said it was a fairer way of having crossover fights. Visit Business Insider's homepage for more stories. LAS VEGAS — One of boxing's most powerful promoters has issued a challenge to the UFC star Conor McGregor — fight the world champion boxer Terence Crawford in a cage, using MMA rules. Bob Arum, the 88-year-old founder and CEO of Top Rank, initially made a two-fight proposal on ESPN in January.See the rest of the story at Business InsiderNOW WATCH: 5 things about the NFL that football fans may not knowSee Also:Deontay Wilder's trainer says meeting the boxer 'has been the greatest thing that ever happened' to himA 22-year-old Brit who has 'the menace of George Foreman' is close to a world title shot against Deontay Wilder, according to his promoterBilly Joe Saunders is terrific, but nobody can beat Saul Alvarez at super middleweight, DAZN stablemate Mikey Garcia says