  We discuss pion pair production in two-photon collisions in two different
kinematical regimes. When both photons are real and at moderately large
center-of-mass energy s we elaborate on partonic transverse momentum and
Sudakov corrections within the hard scattering approach. We also point out the
difference between our approach and that of other authors. When one of the
photons is highly virtual the produced pion pair can be described in terms of a
two-pion distribution amplitude, for which we derive the perturbative limit at
large s.
