In this paper, we prove a quantitative version of the Tits alternative for negatively
pinched manifolds X. Precisely, we prove that a nonelementary discrete isometry
subgroup of Isom(X) generated by two non-elliptic isometries g, f contains a free subgroup of rank 2 generated by isometries fN, h of uniformly bounded word length. Furthermore, we show that this free subgroup is convex-cocompact when f is hyperbolic
