This research examines the effect of the color of a goalkeeper's uniform on perceived size and performance in sports. The main purpose was to determine the impact of particular colors, namely red, yellow, blue, green, and black on the psychological attitudes of goalkeepers during competition. The quantitative approach was used in the study since the participants were asked to guess the size of goalkeepers wearing uniforms of various colors. The results revealed a significant main effect of uniform color on perceived size, with male goalkeepers in red and yellow uniforms estimated to be larger than those in blue (p = 0.008) and green (p = 0.061). In a follow-up experiment, it was found that male goalkeepers were perceived to be 16.8% larger than their actual size (F(1, 85) = 263.748, p < 0.001), while female goalkeepers were perceived as 6.3% larger (mean difference of 10.480, SE = 0.645, p < 0.001). The results show that there is a significant gender stereotype, where male goalkeepers are perceived as larger than female goalkeepers irrespective of the color of the uniform they wear. These results indicate that uniform color can be used as a psychological weapon in sports and that the opponents may be conditioned by the color of the uniforms worn by the athletes. The findings of the study have relevance to the management of sports teams and the design of kits where the use of appropriate colors may be a nonverbal communication edge. However, the generalization of the results as well as the reliability of the results may be limited due to the small number and young age of the participants, restricted color options during the design of the uniform, and other features that may limit the applicability of the research in different sports and cultures.