In this paper we study the problem of robust output regulation for a nonlinear system in the presence of gain-bounded perturbations. The problem in question is approached as a problem of robustly stabilizing, in the presence of gain-bounded uncertainties, a suitable "augmented" plant in which the regulated output drives an appropriate "internal model" of the exosystem. Robust stabilization of the latter is achieved, in turn, by solving an appropriate problem of suboptimal disturbance attenuation.