Stellar mass of the primary galaxy as a function of redshift for our major close pairs sample, colour coded with respect to the galaxy mass ratio in the pair. The primary galaxy is the more massive galaxy of the pair. The circles are pairs in the UDF-Mosaic, triangles in udf-10, and squares in HDF-S. Except in the redshift “desert” (z ~ 1.5−2.8), the mass range probed with MUSE observations does not change significantly with redshift, with a fairly good completeness level between ≈ 10⁷−10¹⁰ M_⊙.