A mast erection system includes a first mast erection apparatus that is adapted to pivotably raise a drilling rig mast of a drilling rig assembly to an intermediate raised position wherein the drilling rig mast is oriented at a first acute angle relative to a horizontal plane, and a second mast erection apparatus that is adapted to further pivotably raise the drilling rig mast from the intermediate raised position at the first acute angle to a fully raised position wherein the drilling rig mast is oriented at a second angle relative to the horizontal plane that is greater than the first acute angle.