This is the only Metallica album that doesn't have an official bass player. The band had parted ways with Jason Newsted, whose last performance with the band was on "I Disappear
," and didn't feel ready to replace him, so longtime Metallica producer Bob Rock (regular collaborator since 1990) played bass on St. Anger
as a one-off deal.
It was only in February 2003, after the album was completed, that Metallica brought in Robert Trujillo to take Newsted's place. Trujillo's first live performance with the band was at San Quentin prison on May 1, 2003.
Rock and Metallica parted ways after St. Anger