Image by Jayegirl99 via FlickrIn the early 80's, it was John McEnroe who let off steam on court. Recently, it was Serena Williams who had been reprimanded for smashing her racket on court. According to his report HERE, due to the intensity of the game, all tennis player suffer from burst of anger that they ultimately have to keep under control.
The level of intensity threshold beyond which the outburst is beyond control varies from individual to individual. Everyday training that they carried out is to control their emotions in order to make them as a professional player. The burst of anger is not peculiar to tennis alone; other games also suffer from the same predicament and read HERE for the reasons why the respective games are prone to have those symptoms.