Updated project metadata. Plant apoplast is the first hub of plant-pathogen communication. Indeed, during interaction, pathogen effectors are recognized by plant defensive proteins and cell receptors and several signal transduction pathways are activated. Within this first contact, a defence response is triggered by the plant involving several extra and intracellular proteins. In grapevine, little is known about the communication between cells and apoplast in the context of plant-pathogen interactions, also apoplast dynamics, particularly considering the role of apoplastic proteins in response to pathogens still remains a blackbox. In this study we focused on 6 hours after Plasmopara viticola inoculation to evaluated grapevine proteome modulation both in the apoplastic fluid (APF) and total leaf tissue. Plasmopara viticola secretome was also assessed enabling a deeper understanding of plant and pathogen communication. Our results showed that oomycete recognition, plant cell wall modifications, ROS signalling and disruption of oomycete structures are triggered in Regent after P. viticola inoculation. Also, our results highlight a strict relation between the apoplastic pathways modulated and the proteins identified in ‘Regent’ total leaf proteome. On the other hand, P. viticola proteins related to growth/morphogenesis and virulence mechanisms were the most predominant. This pioneer study highlights the early dynamics of extra and intracellular communication between grapevine and defence activation leading to the successful establishment of an incompatible interaction