  We develop new gauge-covariant implicit numerical schemes for classical
real-time lattice gauge theory. A new semi-implicit scheme is used to cure a
numerical instability encountered in three-dimensional classical Yang-Mills
simulations of heavy-ion collisions by allowing for wave propagation along one
lattice direction free of numerical dispersion. We show that the scheme is
gauge covariant and that the Gauss constraint is conserved even for large time
steps.
