Apparatus for forming an extended nip between a heated mating roll and a shoe roll for treating a product web, especially a paper web, the shoe roll having a stationary support and a flexible belt which can rotate about the support and, in the area of the extended nip, is supported on a shoe which is guided on the support, forms a press section and has an effective shoe width, and the belt having end sections which are fixed to end walls that are rotatably mounted on the support, in each case at the ends and axially adjacent to but at a distance from a mating face located opposite the effective shoe width of the shoe, the mating roll having a radially protruding support ring, which forms an opposing bearing for the direct support of an outer belt section on the mating roll and consists of a thermally insulating material.