  We use a holographic method to investigate thermalization of a
boost-invariant strongly interacting non-Abelian plasma. Boundary sourcing, a
distorsion of the boundary metric, is employed to drive the system far from
equilibrium. Thermalization is analyzed through nonlocal probes: the equal-time
two-point correlation function of large conformal dimension operators in the
boundary theory, and Wilson loops of different shapes. We study the dependence
of the thermalization time on the size of the probes, and compare the results
to the ones obtained using local observables: the onset of thermalization is
first observed at short distances.
