Tennis is not only a physically demanding sport, but also extremely challenging mentally, so improving the mental abilities of tennis players is one of the basic factors of their training. The complete training of a tennis player is a carefully planned and combined network of activities that include physical, technical, tactical and psychological preparation complemented with proper nutrition. At the level of the game of top tennis players, most of them are endowed with acquired experience, polished technical and tactical knowledge and developed physical abilities, so the mental status of the player is often the decisive factor that determines the difference between a winner and a loser. The athletes themselves rated mental preparation as the most important reason for a successful or unsuccessful performance, three times more than the second-ranked physical preparation, and tennis coaches also agree with their assessment. Tennis champions ranked various psychological characteristics as those that most influenced their performance during the era when they played their best tennis. Tennis players who pay attention to mental preparation develop skills that allow them to develop and improve motivation, concentration, self-confidence and control and regulation of emotions. Some mental abilities have linear influence on tennis player's performance, and some don’t, so it is necessary for each tennis player to search for and achieve the individual optimal level of each of them. Working on mental abilities and learning techniques to control them significantly helps in achieving an optimal psychological state during each phase of competitions. In conclusion, mental preparation is a fundamental element of success in tennis that enables players to reach their full potential and achieve top results.