A Seven-Minute Hellstorm of Gonzo Guitar, Shifting Meters, and Nasty Sax

And about 2 minutes in, you get a somewhat familiar riff.

PS - It ain't just me saying it: Steve Howe on "Heart of the Sunrise": It was Chris [Squire] who wrote the main riff. I always thought the riff was influenced by "21st Century Schizoid Man", but I suppose we got away with it.