Rolling element bearings are keystones of mechanisms, because they are necessary for a proper operation, but remains also the Achilles heel of the system. If any external particle penetrates the contact, the contacting surfaces may suffer from indentation and become thus irreversibly damaged. Solutions must be proposed for reducing the particle entrapment probability. The authors in a past study showed that an ellipticity of the EHL contact perpendicular to the rolling direction leads to an important decrease of the particle entrapment due to more important backflows occurring in the lubricant. An experimental approach with a device combining a classical tribometer and a µ-Particle Image Velocimetry (µ-PIV) visualization system is here used to get measurements on the dynamics of suspended fluorescent particles. It enables an insight on the lubricant flow upstream from different elliptical contacts and allows to explain the drop in particle entrapment in large elliptical contacts.