Tennis, as John McEnroe had said, is a very lonely game. The players are out there in the middle without any teammates to share their joys and sorrows with. Tennis is thus similar to boxing. It's fighting mano-a-mano, only with racquets in hand and a court separating the prize fighters.

And rivalries in this most primal (Yes, I said primal) of sports in gentleman's clothing are essential to take the game forward.