et al. (2001). These authors found that the intermediate elements of CNO, and to some extent even hydrogen and helium, gain importance in driving the winds of O stars at $Z$ $\la$ 1/30 giving rise to a flattening of the O star mass-loss rate versus metallicity relation (see their Fig 5c). Interestingly, the opposite behaviour has been found by Kudritzki (2002), who finds that ${\mbox{$\dot{M}$}}$ decreases even more rapidly at $Z/{\mbox{$Z_{\odot}$}}$ $\la$ $10^{-3}$. The cause of this discrepancy at very low $Z$ in the ${\mbox{$\dot{M}$}}$(Z) behaviour between the two approaches has yet to be identified. It may be related to their treatments of the relevant aspects of the physics of line driving at different levels of sophistication. Kudritzki (2002) parameterizes the radiative force through so-called force multipliers (in an extension of CAK theory), enabling a relatively straightforward solution of the wind dynamics. Vink et al. (2001) calculate the radiative force exactly with a Monte Carlo approach that allows for a detailed treatment of multiple photon scatterings, albeit adopting a pre-described velocity law (but see Vink et al. 1999, Vink 2000). The global approach works very well for OB stars (Vink et al. 2000), and although its validity for WR stars 