Long quantum superstrings in AdS_5 x S^5

Following hep-th/0001204 we discuss the computation of quantum corrections near long IIB superstring configurations in AdS_5 x S^5 which are related to the Wilson loop expectation values in the strong coupling expansion of the dual n=4 SYM theory with large N. We use the Green-Schwarz description of superstrings in curved R-R backgrounds and demonstrate that it is well-defined and useful for developing perturbation theory near long string backgrounds.