[en] We test the renormalization of Wilson operators and the Mandelstam-Leibbrandt gauge in the case when the sides of the loop are parallel to the n, n^* vectors used in the M-L gauge. Graphs which in the Feynman gauge are free of ultra-violet divergences, in the M-L gauge show double divergences and single divergences with non-local Si and Ci functions. These non-local functions cancel out when we add all graphs together and the constraints of gauge invariance are satisfied. In Appendix C we briefly discuss the problems of the M-L gauge for loops containing spacelike lines. (orig.)