A method for determining the beginning of a start phase of an internal combustion engine in a hybrid vehicle, in which a second drive unit drives the hybrid vehicle, the internal combustion engine being started upon reaching a certain drive torque of the second drive unit. In order to always be able to achieve the maximum solely electric driving range of the hybrid vehicle using the second drive unit and simultaneously improve the driving comfort of the hybrid vehicle by optimizing the internal combustion engine start triggering, the internal combustion engine is started when a predicted drive torque of the second drive unit is less than or equal to the drive torque, as instantaneously measured and increased by a torque reserve, of the second drive unit.