Nonlinear modal analysis is slowly becoming a mature tool for improved investigations of flexible structures subject to vibration. Nonlinear modes (NLM) may be defined as non-trivial periodic solutions of autonomous dynamical systems. They are invariant curved subspaces embedded in the original configuration space and share similar properties with their linear and flat counterparts such as eigenfrequencies. The present study takes advantage of their properties to assess the performances of time-stepping techniques dedicated to flexible mechanical systems featuring unilateral contact conditions.