Mumbai had struggled in the early stages, losing wickets at crucial times as Imran Tahir bowled brilliantly but four sixes from Hardik Pandya at the death got them up to 184.
Pune lost Manyank Agarwal early on but a half-century from Ajinkya Rahane and a brilliant, unbeaten 84 from Smith saw the Supergiant home with just a ball to spare.
So here are the highlights, the takeaways and lowlights from Match 2.
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Jos Buttler is comfortably England's best T20 cricketer
Buttler afterwards called Steve Smith the best batsman in the world – but in T20 cricket the England wicket-keeper is not far behind.
After making 38 off 19 balls, he was given out LBW after a thick inside edge and was rightly gutted to walk off without any more runs to his name.
The Lancashire man will have plenty more chances to impress and will not have to worry about keeping with opening partner Parthiv Patel taking the gloves for Mumbai. Expect him to inflate his already-swollen reputation.
Steve Smith was sensational for Rising Pune Supergiant as they chased down 184
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Ben Stokes will learn a lot from the IPL
And boy does he need to.
Stokes had never bowled to Buttler in a T20 match but it's safe to assume he has bowled at him in nets a lot.
Even so, the Durham all-rounder fell into the trap of bowling length and was promptly dispatched firstly over long-on and then, via a trademark ramp, over the wicket-keeper's head.
Steve Smith and MS Dhoni saw Rising Pune Supergiant to an opening IPL win
Rohit Sharma despaired as Mumbai Indians dropped crucial catches
It was reminiscent of that horrible night in Kolkata when Carlos Brathwaite demolished his confidence, albeit to lesser extent.
Stokes responded by bowling even faster and Buttler missed, but England fans will hope the all-rounder learns more than just "bowl fast" from his IPL stay.
Imran Tahir almost didn't get a game
Tahir was the No 1 ranked T20 bowler in the world when he went unsold at February's IPL auction, a mystery to many pundits.
Had it not been for an injury to Mitchell Marsh, he would never have been signed by Pune and might not have appeared in the IPL this year at all.
His value was immediate, picking up the wickets of Jos Buttler, Rohit Sharma, Parthiv Patel – Mumbai's top three batsmen.
Catches still win matches
RCB were guilty of dropping catches yesterday, worst of all when Yuvraj was in the 20s – his 62 was probably the difference between the two sides.
In a tight run-chase with captain Steve Smith well set, Nitish Rana put the Australian down at deep square leg. He was on just 36.
And then, having dropped Pune's best batsmen, Tim Southee put down one of the world's best finishers with an over to go.
In the end it was Smith who hit two sixes in the final over to win the game and finish 84 not out, but dropping either player was not a clever bit of cricket.
Mumbai fans will be hoping the Indians have learned their lesson.