Tennis has a peculiar scoring system. The purpose of this study was clarify the importance of counting one game in tennis matches by studying data from actual games, comprising 42 men's singles matches (907 games) during the Kyushu collegiate tennis championships held in 1997 and 1998. The main criterion for the analysis was the relationship between point-winning at each score and game-winning. It was found that (1) the rate of point-winning by game-winning players was 67.0%, and that the rate of point-winning by opponents was 33.0%. The game-winning players obtained 2/3 of all points. Furthermore (2), the rate of point-winning by players with a leading score was comparatively high at the time of either leading, such as in an up count or a down count, as well as when there was a difference in points at game-point. In particular, the rate of point-winning by game-winning players was significantly high on 0-15 and 15-30. (3) At scores of 30-30 and deuce (i.e. even count), the rate of point-winning by game-winning players was significantly high. These scores led an even count to game-point. These scores also showed a high frequency, and were the key to winning the game. These results suggest that scores of 30-30 and deuce are keys to game-winning, when gaining one point can lead to victory.
