Red Rocks was one of the most gorgeous places in the world to see the Grateful Dead or any other act, a 9,000-capacity natural amphitheater framed by giant sandstone crags (with only gentle benched seating) and a starlit view of Denver twinkling in the distance. Even without the rain that will force the next two shows inside, the night goes liquid. Moving from an “Estimated Prophet” that overflows with chattering Dyna-Rhodes by new keyboardist Brent Mydland, the band flows like fire into the uptempo late-’70s “Eyes Of The World” (around 130 bpm tonight), Garcia again singing an alternate version of the first line (“sleepy summer home”), before the jam bursts open. Led by the butterflying Garcia guitar, the band focuses, blurs, and heads further as Mydland dials in Moog pans and bleeps and the drummers go free.