Debris entrapment in a lubricated rolling-element bearing is a major problem for bearing life improvement. At the same time new types of materials, like ceramics for hybrid rolling elements bearings, have been developed to respond to the current challenges imposed to the machine elements (faster rotational speed, contaminated and chemical environment, electrical or thermal insulation needs). Nowadays, particle entrapment in a steel-steel contact is relatively well known, and depends strongly on operating conditions (load, speeds, slide-to-roll ratio…). The presentation will deal with the analysis of different phenomena leading to the entrapment of spherical steel particles in the case of ceramic-steel contact. Lubricant flow in the inlet zone of the contact is then considered, and trajectories of particles are calculated according to their size and nature.