We consider some basic principles of fluid-induced lubrication at soft interfaces. In particular, we
quantify how a soft substrate changes the geometry of and the forces between surfaces sliding past each
other. By considering the model problem of a symmetric nonconforming contact moving tangentially to
a thin elastic layer, we determine the normal force in the small and large deflection limit, and show that
there is an optimal combination of material and geometric properties which maximizes the normal
force. Our results can be generalized to a variety of other geometries which show the same qualitative
behavior. Thus, they are relevant in the elastohydrodynamic lubrication of soft elastic and poroelastic
gels and shells, and in the context of biolubrication in cartilaginous joints.