On April 1, 1983, METALLICA invited Kirk Hammett to audition as lead guitarist, replacing Dave Mustaine who had been fired just days earlier due to his alcohol abuse and volatile behavior. Hammett, then playing with Bay Area thrash pioneers EXODUS, flew to New York and immediately clicked with James Hetfield, Lars Ulrich, and Cliff Burton. His melodic sensibility and fluid lead style brought a new dimension to the band's sound. Within weeks, Hammett was recording solos for the debut album 'Kill 'Em All,' replacing Mustaine's original parts. The decision proved monumental — Hammett's tenure would span four decades and counting, helping METALLICA become the best-selling metal band in history. Meanwhile, Mustaine channeled his fury into founding MEGADETH, creating one of metal's greatest and most productive rivalries that would push both bands to extraordinary heights.