These transition riffs lead to the entrance of the main riff of the song. It incorporates the slide up to E and the Bb-to-A descent from the previous riffs and restores the rhythmic quality of the intro riff (ties over the barlines, quarter note on A on the third beat). The pattern is repeated three times, and the riff concludes with a power-chord progression on G and F#.
Unlike as in “The Thing That Should Not Be,” where the evolution occurs linearly, the evolution of the theme in “Sandman” takes a more circuitous route. The course of these variations may be summarized as the establishment of the elements of the main riff (first example), the deconstruction of the intro riff to a simple octave ascent (second example), followed by the gradual reinstatement of the original melodic and rhythmic elements and introduction of new elements (third and fourth examples), culminating in the theme of the song (fifth example).