US, Nov. 4 -- Sport has a peculiar way of turning heroes into legends-and, sometimes, legends into their own worst enemies. Behind the glitter of trophies, records and applause lies a less glamorous reality: the human ego. A great sportsperson may possess extraordinary talent, but talent alone does not guarantee greatness.

When confidence crosses the invisible line into arrogance, when healthy competition becomes jealousy, and when personal pride begins to outweigh the interests of the team, even the most formidable careers can begin to unravel.

In sport, sometimes the greatest opponent is not standing across the boundary or on the other side of the pitch; it is standing within. Sport, therefore, presents us with two very different fac...