Previous work has shown that Centrolene savagei is unique among the more than 150 species in the family Centrolenidae in demonstrating large-male mating advantage. However, it is still unknown whether non-random mating in this species is mediated by intrasexual and/or intersexual selection. To disentangle the effect of these selective pressures on mating pattern in this species, we monitored the breeding behavior of individuals in a population located in the department of Quindío, Central Andes of Colombia. We conducted diurnal and nocturnal surveys each weekend between February and July of 2016 in which we documented morphological (i.e., body size) and behavioral (i.e., chorus tenure, parental-care behavior) characteristics of males to determine their relationship with mating success. We corroborated that in this population of C. savagei, larger males obtain a higher number of mates than do smaller males; male body size co-varies positively with chorus tenure and drives this mating pattern. Male body size was not related to higher fertilization efficiency of eggs laid by females, or a higher survival of embryos in clutches cared for by them. In sum, the higher mating success of larger males in the glassfrog C. savagei seems most strongly related to a mechanism of endurance rivalry competition (intrasexual selection) than female choice (intersexual selection) based on egg fertilization efficiency or parental care quality.