An arrangement for washing and dewatering cellulose pulp comprising: a press roll, which is arranged to rotate during operation and which has a perforated outer surface for dewatering the pulp; a stationary guide surface, arranged at a distance from the perforated outer surface of the press roll so as to enclose a portion of the press roll in the circumferential direction of at least around 225° of the press roll's circumference counting from the inlet to the pinch, the stationary guide surface forming a substantially closed vat over this portion; a pulp passage, being defined substantially between the perforated outer surface of the press roll and the stationary guide surface, such that during operation, wherein pulp that is fed into the pulp passage is transported in a direction of rotation and, at the end of the pulp passage, is pressed in a pinch, between the press roll and a second press roll; the washing arrangement involving two substantially similar press rolls, and the pinch being formed between these press rolls, such that a wedge volume is formed close to the nip, into which pulp fed from the pulp passage merges before the merged flows of pulp enter the nip, at least one zone in the pulp passage where a wash liquid is added to the pulp passage and where a wash filtrate displaced by the wash liquid is subsequently drained via the perforated outer surface of the press roll, characterized in that a radial distance between the stationary guide surface and the associated press roll is non-converging over substantially the whole pulp passage enclosed by the stationary guide surface, towards the pinch, and that, close to the pinch, the stationary guide surface includes no holes for liquid to escape, such that the pressure that is build up in the pinch is not lost. a press roll, which is arranged to rotate during operation and which has a perforated outer surface for dewatering the pulp; a stationary guide surface, arranged at a distance from the perforated outer surface of the press roll so as to enclose a portion of the press roll in the circumferential direction of at least around 225° of the press roll's circumference counting from the inlet to the pinch, the stationary guide surface forming a substantially closed vat over this portion; a pulp passage, being defined substantially between the perforated outer surface of the press roll and the stationary guide surface, such that during operation, wherein pulp that is fed into the pulp passage is transported in a direction of rotation and, at the end of the pulp passage, is pressed in a pinch, between the press roll and a second press roll; the washing arrangement involving two substantially similar press rolls, and the pinch being formed between these press rolls, such that a wedge volume is formed close to the nip, into which pulp fed from the pulp passage merges before the merged flows of pulp enter the nip, at least one zone in the pulp passage where a wash liquid is added to the pulp passage and where a wash filtrate displaced by the wash liquid is subsequently drained via the perforated outer surface of the press roll, characterized in that a radial distance between the stationary guide surface and the associated press roll is non-converging over substantially the whole pulp passage enclosed by the stationary guide surface, towards the pinch, and that, close to the pinch, the stationary guide surface includes no holes for liquid to escape, such that the pressure that is build up in the pinch is not lost.