The aim of this article is to study the residual Monge-Amp\`{e}re mass of a plurisubharmonic function with an isolated singularity, provided with the circular symmetry. With the aid of Sasakian geometry, we obtain an estimate on the residual mass of this function with respect to its Lelong number and maximal directional Lelong number. This result partially answers the zero mass conjecture raised by Guedj and Rashkovskii.
Comment: Some typos were corrected. Section 3.1 was rewritten to give a better introduction to Sasakian geometry, and Section 5.3 was added for a variational approach to our results