Partial melting of rocks is seen as a weakening phenomenon capable of drastically reducing the strength of partially melted rocks. This assertion is based on both field evidence and synkinematic partial melting experiments. Experiments at high confining pressure allow partial melting reactions to be passed into the creep domain of solid phases, and limit experimental artifacts. The latest-generation Griggs rigs, equipped with in situ monitoring systems, are a prime tool for advancing our understanding of the couplings between partial melting and deformation, with acoustic monitoring enabling real-time measurement of P-wave velocity through the sample. We plan to study the mechanical behavior of 10% Ms - 90% Qz powder mixtures starting at 750°C and 1.5GPa on the Griggs apparatus at LG-ENS. Post-mortem characterization of deformed samples is based essentially on microscopy and EBSD analysis.