The scene was straight out of Brad Gilbert's bestseller Winning Ugly: Mental Warfare in Tennis.

During a brutal first-round match in 107 degree heat at the Australian Open, opponents Kei Nishikori and Marinko Matosevic each took prolonged bathroom breaks - but not at the same time. The key to winning ugly, as Gilbert would argue, is to make your opponent wait on the court in the heat. If your opponent does this to you, then you should take a break in retaliation and make them wait. While they seethe on the court, you come back fresh. You have then succeeded in annoying your opponent, and your unnerved opponent will start making mistakes. 

This is apparently a trick that men have adapted to use over time, as a new study demonstrates that men (only men were studied) deliberately anger each other to gain advantage and get what they want. 

According to a study published in the journal Proceedings of the National Academy of Sciences by Uri Gneezy, a behavioral economist at the University of California, San Diego, anger can be used strategically to impair an opponent's performance. Of course, anger can also be used to the benefit of a rival. If we sense that, we tend to shy away from the strategy.

Gneezy's study obviously has implications for negotiation. The rational course of action, it appears, is not always the most effective course of action.

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