This study aimed at describing the changes in physical and physiological performance of a two-time World Karate Federation Champion athlete immediately prior to and after a bout simulation. The karateka was submitted to: (a) squat and countermovement jumps, jump squat and bench throw and maximal isometric force tests (half-squat and bench press, pre and post-match); (b) one simulated karate match. Improvements of 1.1% and 2.9% were observed in the squat jump and countermovement jumps, respectively, after the combat simulation. For jump squat, an increase in power production was observed after the simulation (0.6–7.4%). Conversely, for the bench throw a decrease in power was detected after the match (0.5–8.3%). The maximal isometric force increased for the half-squat (10.5%) and bench press exercises (1.6%). The investigated athlete presented quite different characteristics when compared to similarly highly trained peers, and these traits can probably explain his “outlier performance”.