TITLE: Does an exponential map defined on all of $T_p M$ for one $p$ imply completeness?
QUESTION [6 upvotes]: Let $M$ be a connected Riemannian manifold. Hopf-Rinow states that if $\exp_p$ is defined on all of $T_p M$ for all $p \in M$, then $M$ is geodesically complete.
I'm wondering whether it is sufficient for $\exp_p$ to be defined on the whole tangent space for one $p \in M$.
(If you go with the interpretation that geodesic incompleteness comes from "cuts" or "holes" in your manifold, then the exponential map should be able to "see" these.)

REPLY [5 votes]: Yes it is sufficient, as explains Jack Lee in the comment I posted. You can find in his book Riemannian Manifolds: An Introduction to Curvature the following corollary of Hopf-Rinow theorem.

Corollary 6.14: If there exists one point $p ∈ M$ such that the restricted
  exponential map $\exp_p$ is defined on all of $T_p M$, then $M$ is complete.

It is more a corollary of the proof of Hopf-Rinow, not really of the theorem itself.