A method and device are provided for controlling disengagement of an automated vehicle master clutch arranged in a vehicle drivetrain between a vehicle propulsion unit and a step geared transmission. The method includes the steps of determining a first output torque of the propulsion unit prior to initiation of a master clutch disengagement procedure, computing a second output torque of the propulsion unit in dependence of at least the first output torque, and where the second output torque is closer to zero torque than the first output torque, initiating the master clutch disengagement procedure by initiating an oscillation in drive shafts by abruptly altering propulsion unit output torque from the first to the second output torque, and disengaging the master clutch when the oscillation has reached a first oscillation turning point. Benefits can include faster gear shifting and better comfort with maintained transmission durability.