Fluid pressure as fallback boundary condition

Hi
I am squeezing a poroelastic sphere (structural mechanics coupled to Darcy's law) with a rigid, impermeable flat surface and I find that it is not possible to establish the fluid pressure at the contact boundary of the sphere as a fallback BC. I have the impression ABAQUS would allow me to do this but I can't believe COMSOL would not have the capability. Anyone has any idea how to get around this?

Cheers

Mauricio