This paper proposes a game theoretic approach to modelling tactical changes of formation in an association football match. We use a Poisson regression model to evaluate the offensive and defensive strengths of the formations of teams for scoring or conceding a goal by means of the maximum likelihood method. We then develop a mathematical formulation to express quantitatively the tactical changes of formation as a zero-sum game by taking account of both teams’ decisions. We demonstrate how the managers’ decisions affect the probability of winning the match using real data of the J League, by showing the four cases of the quality of both managers’ decisions, depending on whether they each use their best or worst strategies.