Originally Posted by *Sparkle*
It's disrespectful to his opponent to withdraw, denying his opponent a proper victory, just to save himself the shame of a defeat.
That's complete nonsense. You clearly haven't played any serious competitive tennis. His opponent will be glad he doesn't have to put anymore mileage on the body to win the game. The tour is long, and if you can save yourself a grind, you'll do so.