We study the evolution of a massive black hole pair in a rotationally supported nuclear disc . The distributions of stars and gas mimic the nuclear region of a gas–rich galaxy merger remnant . Using high–resolution SPH simulations , we follow the black hole dynamics and trace the evolution of the underlying background , until the black holes form a binary . We find that the gravitational perturbation of the pair creates a core in the disc density profile , hence decreasing the gas-dynamical drag . This leads the newly formed binary to stall at a separation of \sim 5 pc . In the early phases of the sinking , black holes lose memory of their initial orbital eccentricity if they co–rotate with the disc , as rotation of the gaseous background promotes circularization of the black hole orbits . Circularization is efficient until the black holes bind in a binary , though in the latest stages of the simulations a residual eccentricity \mathrel { \hbox to 0.0 pt { \lower 3.0 pt \hbox { $ \sim$ } } \raise 2.0 pt \hbox { $ > $ } } 0.1 is still present . Black holes are treated as sink particles , allowing for gas accretion . We find that accretion strongly depends on the dynamical properties of the black holes , and occurs preferentially after circularization .