A complete removal and reinsertion of instruments is avoided when the instruments are initially not correctly positioned during a minimally invasive operation on a bone, in particular a vertebra of the spine. This aim is achieved by an instrument set for spinal operations, including a guide rod, which has a cavity extending along the axis of the guide rod, and a guide tube, which can be received in the cavity of the guide rod, wherein the guide rod has a distal lip, which is arranged eccentrically to the cavity and/or to a center axis of the guide rod.