  We find that Coulomb focusing persists even when the Coulomb field is barely
noticeable compared with the laser field. Delayed recollisions proliferate in
this regime and bring back energy slightly above the 3.17 U_p high-harmonic
cutoff, in stark contradiction with the Strong Field Approximation. We
investigate the nonlinear-dynamical phase space structures which underlie this
dynamics. It is found that the energetic delayed recollisions are organized by
a reduced number of periodic orbits and their invariant manifolds.
