A method and control system are disclosed for adjusting orientations of knockdown rollers for sugarcane harvesters. An upper knockdown roller may be moved along a first adjustment path using a first actuator. A lower knockdown roller may be moved along a second adjustment path using a second actuator. A substantially tangential alignment may be maintained for an outer diameter of the upper knockdown roller and an outer diameter of the lower knockdown roller with respect to a reference point along a cutting path of the base cutter assembly, during or after movement of the upper and lower knockdown rollers.