An axial plain bearing assembly includes a thrust ring provided for common rotation with a rotary component. The thrust ring has a radial seal face on an end face thereof for co-operating with a radial seal face of a non-rotational seal ring of a gas-lubricated mechanical face seal assembly for sealing said rotary and stationary components against each other. A plurality of peripherally spaced gas-pumping grooves is formed in at least one of the radial seal faces of the thrust and non-rotational seal rings. A mass ring connected with the thrust ring is provided at an axial distance from the thrust ring. The mass ring is configured and adapted to exert a balancing force on the thrust ring under centrifugal forces acting on the mass ring during common rotation of the mass and thrust rings to compensate for thermal distortion of the thrust ring during operation.