Young athletes face mental challenges both in competitive sports and in school. High self-efficacy and self-regulation competence contribute to an individual's ability to successfully master these challenges. The present study links the domains of competitive sports and academic education by investigating the relationships of self-efficacy and self-regulation to performance in mathematics lessons. Here, we compare competitive rowers (n = 239) and "regular"students (n = 171; total N = 410). The competitive rowers showed a higher subjective expectation of self-efficacy, which in both groups had a positive effect on mathematics grades. While self-regulation had a mediating effect on the competitive rowers in this context, we observed no significant effect for the regular students. The study provides evidence that competitive athletes are apt to use psychosocial resources fostered by professional sports training across domains.