  We calculate the potential contributions of the motion of binary mass systems
in gravity to the fifth post--Newtonian order ab initio using coupling and
velocity expansions within an effective field theory approach based on Feynman
amplitudes starting with harmonic coordinates and using dimensional
regularization. Furthermore, the singular and logarithmic tail contributions
are calculated. We also consider the non--local tail contributions. Further
steps towards the complete calculation are discussed and first comparisons are
given to results in the literature.
