Game Theoretic Approach to Analyze Japan’s “Keep Rolling the Ball” Tactic Used in the 2018 FIFA World Cup Group Stage Final Matches in Russia Nobuyoshi Hirotsu and Ayako Komine [Received April 5, 2019 ; Accepted April 6, 2020]  During the last 10 minutes of the Group H final match of the 2018 FIFA World Cup, Japan was one goal behind Poland. At the same time, Senegal was also one goal behind its opponent. If both teams were defeated by one goal, Japan would qualify to move forward based on fair play points. However, a second goal by Poland would eliminate Japan in the group stage. Therefore, for these 10 minutes, Japan kept rolling the ball between their defense and midfield. In this study, we analyze this incident from the standpoint of game theory to quantitatively evaluate the quality of Japan’s tactical decision to keep rolling the ball. We model this situation by estimating the scoring rate based on the number of goals scored in the group stage, and calculate the probability of qualifying. We assume that Japan and Poland can choose their tactics, “attack” or “keep rolling the ball,” and compare their expected results. According to our calculation, the scoring rate was estimated to be 0.0307 goals per minute. If Japan chose to “attack,” the probability of qualifying would be 0.676. However, if Japan chose to “keep rolling the ball,” the probability would increase. Therefore, Japan’s choice to “keep rolling the ball” during the last 10 minutes appeared to increase their probability of qualifying; thus, Japan made a rational decision in this situation. Keywords: FIFA World Cup, game theory, keep rolling the ball, tacticc [Football Science Vol.17, 56-68, 2020]