A sports boot, particularly for gliding sports, of the type including a rigid sole, an external upper, and a removal liner, the external upper including a first portion made of a rigid and substantially non-flexible material including at least one heel stiffener; a second portion, attached to the first portion and/or to the sole, made of a substantially rigid and flexible material; a third portion attached to the second portion and made of a flexible material. The second portion includes a collar adapted to at least partially surround the user's ankle, and a vamp. The third portion includes a saddle attached to the vamp, and on which a device for tightening the forefoot is arranged. The third portion can also include two flaps attached to the collar, and on which a tightening device is arranged.