Yang et al. explored the role of intrinsic disorder in the development of the pathogenicity in the RXLR AVR2 effector of Phytophthora infestans. Their results support the notion that intrinsic disorder is important for the effector function of pathogens and demonstrate that SLiM-mediated protein-protein interaction in the C-terminal effector domain might contribute greatly to the evasion of resistance-protein detection in P. infestans.