  We extract the heavy-quark diffusion coefficient \kappa and the resulting
momentum broadening <p^2> in a far-from-equilibrium non-Abelian plasma. We find
several features in the time dependence of the momentum broadening: a short
initial rapid growth of <p^2>, followed by linear growth with time due to
Langevin-type dynamics and damped oscillations around this growth at the
plasmon frequency. We show that these novel oscillations are not easily
explained using perturbative techniques but result from an excess of gluons at
low momenta. These oscillation are therefore a gauge invariant confirmation of
the infrared enhancement we had previously observed in gauge-fixed correlation
functions. We argue that the kinetic theory description of such systems becomes
less reliable in the presence of this IR enhancement.
