Hales pummelled the shorter square boundaries while Buttler was equally dismissive of India's bowlers in a record-breaking unbroken stand of 170 as England claimed a scarcely credible 10-wicket win.
India were viewed as marginal favourites to set up a mouth-watering marquee match against Pakistan at the MCG on Sunday but Hales (86 not out off 47 balls) and Buttler (80no off 49 deliveries) disabused them of that notion in jaw-dropping fashion.
While England had yet to click into gear, they were battle-tested in getting out of the Super 12s and they delivered close to the complete performance in front of a 40,094 largely pro-India attendance.
Hardik Pandya gave a glimpse of what was to come from England's openers, slapping 63 off 33 balls in India's 168 for six, with some audacious hitting at the death helping his side add 88 in the last seven overs.
Adil Rashid stunted India's charge, taking one for 20 in the middle overs, as England made light of the absences of injured pair Mark Wood and Dawid Malan.