Given a closed subset Λ of
the open unit ball B1⊂ ℝn for n ≥ 3, we consider a complete Riemannian metric g
on B1∖ Λ of constant scalar curvature equal to n(n − 1) and conformally related to
the Euclidean metric. We prove that every closed Euclidean ball B⊂ B1∖ Λ is convex
with respect to the metric g, assuming the mean curvature of the boundary ∂B1 is
nonnegative with respect to the inward normal.