A symmetry result for the p-Laplacian in a punctured manifold

Let M be a Riemannian manifold such that its geodesic spheres centered at a point a∈M are isoperimetric and the distance function dist(⋅,a) is isoparametric, and let Ω⊂M be a bounded domain. We prove that if there exists a lower bounded nonconstant function u which is p-harmonic (1