Metabolite profiles based on GC/MS were used to study the temporal dynamics of metabolites in potato leaves following pathogen inoculation. In the polar and non-polar plant extracts a total of 106 consistent peaks were detected, of which 95 metabolites were tentatively identified. Following pathogen inoculation, the abundances of 42 metabolites were significantly increased or decreased, and these metabolites were designated as Pathogenesis-Related (PR) Metabolites. Factor analysis of the abundance of 106 metabolites identified four plant-pathogen interaction functions: (i) homeostasis; (ii) primary defence; (iii) secondary defence; (iv) collapse of primary and secondary defence responses. During the primary and secondary defence phases, dramatic changes in the amino acids, known precursors of several plant defence-related metabolites, were observed. Plausible satellite-networks of metabolic pathways leading to the up-regulation of these families of amino acids and other secondary metabolites, and their potential application for the evaluation of horizontal resistance in potato against the late blight pathogen is discussed.