Shredder Steve Vai and actor Ralph Macchio had the most epic guitar battle in rock history onscreen in the finale of Crossroads, blending blues, metal and classical. However, behind the scenes there was a lot going on for the actors, and it actually took Vai to quite a dark place.

In the scene Vai’s character Jack Butler plays in full-on 80s shred metal style, while Macchio’s character Eugene Martone plays tasteful blues slide guitar and breaks into a beautiful classical section to clinch the battle. The dramatic scene brings the film to its fiery conclusion, with Martone fighting for his mentor’s soul against the villain Butler, who sold his soul to the devil for his fiendish guitar skills.

Both audio parts in the guitar duel were played by Vai, showcasing his versatility as a player and famous virtuoso skills. However Macchio can actually play guitar, and he did play in the shots seen in the movie, as the director hired guitarist Arlen Roth to teach him so his playing would look convincing onscreen.

Screenwriter John Fusco explained to American Blues Scene that much of the audio is dubbed but that Macchio’s playing can actually be heard in some scenes, commenting “I want to emphasize that Ralph did much of his own playing and it was impressive. He is a smart and diligent kid.” Vai later reprised some of the parts from the guitar duel live in concert in South Korea, which you can hear below.

Vai really dug deep to play the devilish Butler, telling Guitar World that there was a time in his life where “I was very willing and able to project a very dark aura. I discovered that it was having a detrimental effect on my mental and physical health and I actually spiraled into a black hole. Fortunately for me, I was able to claw my way out after several years.”

The virtuoso said that during the making of Crossroads, which was his first time acting, he again went to that dark place to inform his performance, saying that “it was difficult because it’s easy to be sucked back into that way of thinking and behaving again. The music was more or less secondary to the attitude. I don’t usually go to that particular place very much anymore. You become what you create, and in those early days I was creating a lot of dark stuff.”

Vai observed that fans responded to his role in the film because “I was projecting so much intensity into the character. Kids respond to that kind of thing.” He added that the idea of the dual and the music itself also played a big role in the enduring popularity of the scene.