85The examination of conditions of competition must be based not only on existing competition between undertakings already present on the relevant market but also on potential competition, in order to ascertain whether, in the light of the structure of the market and the economic and legal contexts within which it functions, there are real concrete possibilities for the undertakings concerned to compete among themselves or for a new competitor to enter the relevant market and compete with established undertakings (Case C-234/89Delimitis [1991] ECR I-935, paragraph 21; Joined Cases T-374/94, T-375/94, T-384/94 and T-388/94European Night Services and Others v Commission [1998] ECR II-3141, paragraph 137; and Case T-461/07Visa Europe and Visa International Service v Commission [2011] ECR II-1729, paragraph 68).