Gender differences in tennis have sparked a great deal of heated debate. Using data from the 24 top men’s and 23 top women’s singles tournaments in 2010, we find a gender difference in the competitiveness (tightness) with regard to the final score of tennis sets. However, when using two physical variables (height and body mass index) that have not been investigated in this context before and controlling for the physical characteristics of the players, this gender difference completely disappears. Moreover, this result remains robust in propensity score analysis. To narrow this disparity between the number of games in men’s and women’s sets, it might be worthwhile for tennis authorities to consider making some changes in court conditions on a gender basis.