Machine Head frontman/guitarist Robb Flynn said having his music idol Hetfield playing live with his band was 'one of the highlights of our musical lives.'
Hetfield ran on stage in Oberhausen, Germany to perform the Machine Head track 'Aesthetics Of Hate' from the band's latest album 'The Blackening.' Machine Head have been the main support act on Metallica's lengthy world tour.
Flynn told Blabbermouth.net: "James and I were hanging out in our dressing room talking, and we have some of those little MicroCube battery-powered practice amps set up, and a small electronic drum kit set up. I was warming up on guitar and he just jumped on the drums and played 'Aesthetics Of Hate'! After we wrapped up jamming, he asked me, 'When are we going to jam it onstage?' It was like, 'F*CK YEAH!!'"
"It was seriously amazing! There was actually a point when we were rocking out together, and I just reached over and grabbed him by the shoulders and yelled, 'This is amazing!'"
View footage of the performance below.