Mark McCormack was the first man to view sport through the prism of business. Widely acknowledged as the originator of an industry, McCormack’s IMG company has remained the preeminent agency in sport and has become known as something of a university for young executives looking to forge a career in the field. In this exclusive article, Donald Dell, McCormack’s fellow Yale graduate, the first man to follow in his footsteps, his chief adversary, and his lifelong friend, gives his personal account of the man behind the business.