Athletes are under pressure to appear tough. However, when injured, being tough is not always in the athlete's best interest. The purpose of this study was to explore the relationship between mental toughness and self-compassion in a sport injury context. To gain a deeper understanding of their relationship, coping resources, self-criticism, and self-esteem were also incorporated into the analyses. A cross-sectional sequential explanatory mixed methods approach was used to address this purpose. In the quantitative phase, men and women athletes who were currently injured (n = 81) completed measures of mental toughness, self-compassion, coping resources, self-esteem, and self-criticism. Results from a hierarchical multiple regression analysis revealed that self-compassion was a significant predictor of mental toughness (?R2 = .07, p < .01), coping resources (?R2 = .10, p < .01), and self-criticism (?R2 = .06, p < .01), beyond the effects of age and self-esteem. Four athletes who self-identified as being mentally tough and self-compassionate in the quantitative phase made up the collective case study. Thematic analysis generated two themes: (a) self-compassion facilitated mental toughness and (b) mental toughness was needed to be self-compassionate in sport. The trustworthiness of these findings was supported through triangulation, reflexivity, and peer debriefing. These findings are consistent with recent research (see Wilson et al., 2019) that suggests self-compassion is needed to be mentally tough, and vice versa. Future research may look to observe the relationship between mental toughness and self-compassion over time.