A method and drive train for performing a gearshift from a first gear to a second gear in a vehicle provided with a manual or automated manual transmission is provided. A drivetrain incorporating the automated manual transmission includes an engine, connected via a clutch to an electric motor/generator, which in turn is connected to the manual or automated manual transmission and wherein the electric motor/generator is connected to a battery, other energy storing devices or a heating element. The method includes controlling the motor/generator to absorb a torque equalling the torque provided by the engine, such that the manual or automated manual transmission transfers a only minor, or no, torque, disengaging the first gear, controlling the torques absorbed by the motor/generator and provided by the engine such that an engine speed correlates to the engine speed necessary for propelling the vehicle at the second gear, and engaging the second gear.