The next excerpt from Allen Fox new book “Tennis: Winning the Mental Match”.

The “Golden Rule” of tennis is the one simple rule that, if followed, will keep you out of more trouble than anything else. It is:  Never do anything on court that doesn’t help you win. Granted, it sounds absurdly obvious, but few people consistently follow it. Adhering to this rule requires one to test any action before taking it with the simple question, “Will this help me win?” If the answer is not yes, don’t do it.
The great players rarely lose track, at least at some level, that the object of the game is to win the match. The average player, by contrast, often seems mindless of this elementary fact. Yet even professionals get caught up in the emotions of the match on occasion and forget.
A truly bizarre example of what can happen was provided by my friend, Jeff Tarango, a brilliant, funny, Stanford-educated tennis professional at Wimbledon in 1996. Tarango, then 26 years old, had never before won a match at Wimbledon. But this year he was in the third round and had an excellent chance of reaching the round of 16 because he was playing Alexander Mronz of Germany, whose name in the tennis world was hardly a household word.
During the match Tarango hit what he thought was an ace, but it was called a fault. While fruitlessly trying to convince the umpire to overrule the linesman, Tarango was heckled by the crowd. Angrily he told them to “Shut up.” The umpire gave him a code violation for “audible obscenity.” Although it only amounted to a warning, this so infuriated Tarango that he demanded the referee supervisor come to the court. The supervisor came and ruled that the warning would stand. Now enraged, Tarango called the umpire “the most corrupt official in the game” and was promptly assessed a point penalty for verbal abuse, costing him the game. At this Tarango blew his top, shouting, “That’s it. No way. That’s it.” He picked up his bags, stalked off the court, and entered the history books as the first player in the Open era to default himself at Wimbledon. To make matters worse (yes, it’s always possible), Tarango held a press conference at which he justified calling the umpire “corrupt” by accusing him, on the basis of hearsay, of having, in the past, “given” matches to players who were his friends.
Let’s tote up the damages. First, Tarango threw away an excellent chance to advance in the tournament since he was, after all, favored in the match. Second, he was defaulted in his mixed doubles, which did not endear him to his partner. Third, it cost him, in fines and lost additional prize money, an amount estimated to be in the neighborhood of $50,000, a considerable sum to a player who was not one of the stars of the game. Finally, his public image was not enhanced by making himself look like an overgrown brat who would have been well served by a few good spankings as a child. All in all it was not one of Tarango’s better afternoons, the object of the game (to win the match) having apparently slipped his mind.
With all these damages accruing as a result of his actions, one might reasonably wonder how a man of Tarango’s substantial intellect could have so completely lost track of his obvious goals? The answer is that his actions were driven by fears of failure (he was losing), exacerbated by the accumulated stress and emotion of the situation. Quitting was his unconscious way of escaping from an excessively stressful situation that he feared would end badly.
If you don’t believe this, picture the following thought experiment: God appears over Tarango’s shoulder and whispers in his ear that he is guaranteed to win the match. Now, what would Tarango have done? He might still have fought with the umpire, but I would bet a lot of money that he would not have left the court and defaulted. (For honesty’s sake, I must confess that during my playing career I did some things in tournaments that were almost as counterproductive as Tarango’s actions. Under sufficient pressure, all of us are quite capable of making some very emotional and foolish decisions).