Researchers have simulated supercooled liquids subjected to Couette shear flow. The rapid drop in viscosity under shear was related to the liquids' two-body structural entropy. The study showed that the structural anisotropy along the extensional direction of the shear flow, measured using the two-body entropy, could fully describe sheared dynamics and shear thinning. These results may uncover the mechanism behind an old problem at the heart of fluid physics, shear thinning.