When you've been as insanely successful as Metallica, you've obviously played your cards right over the years. That said, there's one opportunity that to this day drummer Lars Ulrich fiercely regrets turning down: a chance to soundtrack two pivotal fight scenes in director Quentin Tarantino's cult classic flick, 'Kill Bill.'

Ulrich -- who calls the decision "probably the single biggest mistake I’ve made in the creative department" -- details the whole experience in a piece he wrote for Newsweek magazine. He describes getting pitched the idea after meeting Tarantino for dinner one night in the band's hometown of San Francisco.

"One of the most surreal 30 minutes of my life," the drummer writes, "was having Q.T. six inches from my face, eyes dancing, intensely animated, explaining in intricate detail how he had written and choreographed the two main fight scenes in the film to the Metallica songs 'Enter Sandman' and 'Sad but True.'

"Fists would impact faces on accents. Kicks would land on cymbal hits. Bodies would twirl along with the rhythm of the music. Tarantino’s next-level movie magic married to Metallica music, all turned up to 11."

Ulrich pictured the scenes in his head and envisioned "true cinematic poetry in motion," he continues. "The greatest marriage between music and film the world had ever seen." That is, until Tarantino actually sent him the script, and Ulrich delved into its 180 pages with what was likely a blank stare on his face.

"I had never encountered a narrative like this, set in, to me, a very foreign culture of martial arts and Asian myths," Ulrich admits. "I just couldn’t wrap my thick Danish head around it ... I sat there somewhat bewildered and felt very uncool for not getting it."

Ultimately, Ulrich "experienced a rare inability to pull the trigger," a deal was never struck and Tarantino's bold vision of melding Metallica and martial arts on the big screen for 'Kill Bill' never happened. "Of course 'Kill Bill' turned out to be above and beyond brilliant, as have Tarantino's subsequent movies, which have all been a significant part of my life in the 2000s," Ulrich concludes. "To this day I still worship the ground Q.T. walks on."