CC10 at O (alpha-s): QCD corrections to e+ e- ---> mu- anti-muon-neutrino u anti-d at LEP-2 and the Next Linear Collider.

QCD one-loop corrections to the semileptonic process $e^+ e^- \to \mu^- \bar \nu_\mu u \bar d$ are computed. We compare the exact calculation with a ``naive'' approach to strong radiative corrections which has been widely used in the literature and discuss the phenomenological relevance of QCD contributions for LEP2 and NLC physics.