Bob Rock first impressed Metallica through his work on Mötley Crüe's Dr. Feelgood before producing The Black Album.
Dr. Feelgood was Mötley Crüe's 1989 studio album, and Rock's production helped make it a major commercial success. Metallica heard the record's polished but powerful sound and believed Rock could help them make their strongest album yet.
The choice represented a change from the band's earlier production partnership with Flemming Rasmussen, who had worked on Ride the Lightning, Master of Puppets, and ...And Justice for All. Rock brought different studio methods and challenged the musicians to perform more collaboratively.
His approach was demanding. He asked the band to record together more often, encouraged live-feeling takes, and pressed James Hetfield to improve the lyrics. The process generated tension, but it also helped produce the direct, spacious sound associated with The Black Album.
Rock later became an important recurring collaborator in Metallica's career, although the sessions for this album were famously difficult for both the band and producer.