The identification of the CFT dual of string theory in AdS3 is a long-standing open problem, and little is known outside of very special cases. Recently, a (perturbative) CFT dual for bosonic string theory in AdS3 was proposed, based on a deformed symmetric product CFT. By computing the partition function of long strings in the bulk, I will argue how the worldsheet path integral naturally organizes itself into the coulomb-gas expansion in the dual CFT, effectively deriving the duality from the worldsheet.