In the first part of the master's thesis, we have examined theoretical concepts of marketing in sport, personal branding and social networks. We have examined the process of creating a personal brand, what is a strong personal brand, and who are football players or athletes as personal brands. We have also studied social networks, the importance of communicating of athletes on Facebook, and why Facebook affects a personal brand. After reviewing the literature, we emphasized the purpose of the task, the goals of the master's thesis and the hypothesis of the master's thesis. We have successfully defined sports marketing, the theory of personal branding in sport, and that the rise of personalized brands is influenced by communication through Facebook. The second part contains our own research, which began with the analysis of the content. We studied the personal brands of Lionel Messi, Cristiano Ronaldo and Neymar, for which we have created five hypotheses. The hypotheses were verified by linear regression analysis and the method of statistical verification of assumptions. We also used the ANOVA test and test groups to detect significant differences in responses on Facebook. Based on the results obtained from these analyzes, we therefore conclude that Facebook as a social network has a strong influence on the personal brand of football players and that the Internet and digital communication are now an indispensable part of all areas of our lives, where neither sport is excluded. With the help of literature and our own research, we have confirmed our assumption that personal brands of footballers (and other athletes) are so powerful also because of the presence on social networks, especially on Facebook.