An apparatus for hot filling or warm filling comprising a blowing machine, a filling machine, a capping machine, a tilting machine, a cooling tunnel, wherein there is provided a compression machine configured to apply an axial compression force to a collapsible thermoplastic container along a longitudinal axis thereof, wherein said compression machine is positioned between the blowing machine and the filling machine, or between the filling machine and the capping machine, or after the cooling tunnel, or wherein the filling machine is also the compression machine, or wherein the capping machine is also the compression machine, wherein the collapsible thermoplastic container is designed for a hot filling or warm filling process and comprises: - a body provided with a shoulder, - a neck, provided with a circular upper end defining an opening at a first side of the body, and with a neck ring, - a base, defining a base plane at a second side of the body opposite to the first side, the body having a peripheral groove, between the neck and the middle of the container along the longitudinal axis, comprising a first side, proximal to the neck, and a second side, distal from the neck, whereby the first side comes into contact with the second side, thus reducing the internal volume of the container, when the axial compression force is applied along the longitudinal axis, the compression machine comprising: - at least one lower body (112, 204, 304) having a surface designed to be a resting surface for the base of the collapsible thermoplastic container; - at least one upper body (108, 116, 118, 119, 202, 212, 308) designed to contact a portion of the collapsible thermoplastic container above the peripheral groove; so that the collapsible thermoplastic container can be held in an upright position by the at least one lower body (112, 204, 304) and the at least one upper body (108, 116, 118, 119, 202, 212, 308), - actuating means for actuating the at least one lower body (112, 204, 304) and/or the at least one upper body (108, 116, 118, 119, 202, 212, 308), in order to apply said axial compression force in order to make the first side to come into contact with the second side, thus reducing the internal volume of the collapsible thermoplastic container. - a body provided with a shoulder, - a neck, provided with a circular upper end defining an opening at a first side of the body, and with a neck ring, - a base, defining a base plane at a second side of the body opposite to the first side, - at least one lower body (112, 204, 304) having a surface designed to be a resting surface for the base of the collapsible thermoplastic container; - at least one upper body (108, 116, 118, 119, 202, 212, 308) designed to contact a portion of the collapsible thermoplastic container above the peripheral groove; so that the collapsible thermoplastic container can be held in an upright position by the at least one lower body (112, 204, 304) and the at least one upper body (108, 116, 118, 119, 202, 212, 308), - actuating means for actuating the at least one lower body (112, 204, 304) and/or the at least one upper body (108, 116, 118, 119, 202, 212, 308), in order to apply said axial compression force in order to make the first side to come into contact with the second side, thus reducing the internal volume of the collapsible thermoplastic container.