  It is shown that the deformed Seiberg-Witten curve equation after Fourier
transform is mapped into a differential equation for the AGT dual 2d CFT
cnformal block containing an extra completely degenerate field. We carefully
match parameters in two sides of duality thus providing not only a simple
independent prove of the AGT correspondence in Nekrasov-Shatashvili limit, but
also an extension of AGT to the case when a secondary field is included in the
CFT conformal block. Implications of our results in the study of monodromy
problems for a large class of $n$'th order Fuchsian differential equations are
discussed.
