  We have calculated the Wandzura-Wilczek contribution to the twist-3 part of
$\gamma^*\gamma\to 2\pi$ amplitude. It describes interaction of the
longitudinally polarized virtual photon with the real one, and it is suppressed
by 1/Q, where $Q^2$ is the virtuality of the $\gamma^*$, as compared to the
twist-2 contribution. We have found that, in the Wandzura-Wilczek
approximation, factorization applies to the twist-3 amplitude.
