In 1973, Joe Satriani was giving guitar lessons and one of his students was Steve Vai.
The lessons obviously stuck as they both went onto careers in music, not to mention being friends and collaborators on stage, including the recent G3 tour. But, they never collaborated in the studio until now.
On March 29th they will a new song, the six-minute “The Sea of Emotion, Pt. 1”. It will be accompanied by a video directed by Satriani's son, ZZ Satriani. You can see a clip of it on YouTube.