[en] Microscopic Mottelson-Nilsson method extended for rotating light nuclei is used to obtain the yrast lines of ⁴⁰⁴²Ca and ⁴⁶Ti up to very high spins. This method, apart from being economical, automatically accounts for the change of diffuseness with spin (which is most important for light nuclei). The calculated yrast lines for the above nuclei have been searched for high spin isomers, i.e., cold oblate configurations. They are also discussed in connection with the empirical fusion bands. Since they are found to lie below the fusion bands extracted from the measured fusion cross-sections, it is concluded that the yrast-line limitations cannot be responsible for the observed drop of fusion cross-sections below the reaction cross-sections at high energies in this mass region. (Auth.)