Objectively identical outcomes can carry different subjective value depending on the relational context in which they occur. Across three studies, we examined how rivalry shapes the perceived value and subsequent consequences of winning and losing in professional football. Studies 1a and 1b showed that prestigious rivalries were judged more meaningful than regular matches and were assigned a subjective value of approximately four points. Participants also expected a prestigious victory to improve performance in the following match, and a prestigious defeat to impair it. Study 2 tested these beliefs using preregistered archival analyses of 39,148 matches played over 26 seasons in Europe’s five major football leagues. Contrary to the anticipated positive momentum, teams were less likely to win their next match after a prestigious victory than after a regular victory, and less likely to win after a prestigious victory than after a prestigious defeat. The effect was confined to the next match and was not explained by home–away patterns; prestigious defeats did not differ reliably from regular defeats. Thus, rivalry creates a subjective premium, followed by a short-lived performance cost for the winner, which may result from complacency, concentrated effort in the focal contest, or increased attention for losses.