Over the last years, the increasing use of presumptions in EU competition cases has facilitated a shift of the burden of proof away from the authorities. Exclusivity rebates offered by a dominant company are a good example of the use of such presumptions. The Intel judgment of the Court of Justice of the European Union provides a good opportunity to discuss the role of presumptions in Article 102 TFEU and the implications for the burden of proof. In this article, I analyse how defendants in exclusivity rebate cases can rebut the presumption of illegality in practice, with a special focus on the efficiency defense.