A method and apparatus for planarizing a microelectronic substrate. In one embodiment, one surface of the microelectronic substrate is engaged with a planarizing pad and the opposite surface of the microelectronic substrate is positioned proximate to a substrate support. A bearing liquid, such as a planarizing liquid, is directed toward the second surface of the microelectronic substrate to form a liquid bearing between the substrate and substrate support. The microelectronic substrate can precess relative the substrate support as the substrate support moves relative to the planarizing pad. The substrate support can include a sensor to determine a characteristic, such as a thickness, of the liquid bearing. In another embodiment, a portion of the liquid bearing can be removed from the second surface of the microelectronic substrate to control the thickness of the liquid bearing and/or to remove particulate matter from the liquid bearing.