Metaperceptions constitute estimations that one person holds about another person's perceptions. This study draws from and extends Lent and Lopez's (2002) tripartite model of relational efficacy, to present conceptual and empirical evidence for the role of self-efficacy as a metaperception (Estimations of the Other person's Self-Efficacy; EOSE) within coach–athlete and athlete–athlete contexts.Semi-structured interviews were conducted with 24 members of international-level coach–athlete and athlete–athlete dyads. The data were subjected to content analysis.Results revealed insight into the means through which dyad members form EOSE appraisals (i.e., antecedents), namely via perceptions regarding ‘the other’ (e.g., his/her verbal communication) and the dyad as a whole (i.e., mastery achievements as a dyad). EOSE was also reported to be aligned with important indices of individual and relationship functioning in the form of intra-personal (e.g., personal motivation) and interpersonal (e.g., relationship persistence intentions) outcomes. Overall, findings suggest that EOSE perceptions may represent an important relational efficacy construct within sporting contexts, and implications for theory advancement as well as applied considerations for supporting close relationships in athletic settings are discussed.