  F. Gehring and W. Ziemer proved that the p-modulus of the family of paths
connecting two continua is dual to the p^*-modulus of the corresponding family
of separating hypersurfaces. In this paper we show that a similar result holds
in complete Ahlfors-regular metric spaces that support a weak 1-Poincar\'e
inequality. As an application we obtain a new characterization for
quasiconformal mappings between such spaces.
