India edged past Australia in a high-scoring last-ball thriller in the first T20 in Visakhapatnam.
India lost three wickets in three balls in the last over when they needed only two runs to win.
Rinku Singh smashed the last ball for six to seal victory in emphatic style, only for it to be called a no-ball, which was the winning run.
The five-match T20 series has started just four days after the teams played in the 50-over World Cup final.
Australia won the World Cup by six wickets but here both teams were much changed, with Australia's Josh Inglis and Steve Smith and India captain Suryakumar Yadav the only players involved from the final.
And all three players made key contributions: wicketkeeper Inglis smashed 110 from 50 balls, including eight sixes and 11 fours to set up Australia's imposing 208-3, while Smith made 52 from 41 balls at the top of the order.
Suryakumar then struck 80 from 42 balls in a stand of 112 with Ishan Kishan, who made 58, as the pair led a recovery from 22-2.
When Suryakumar was dismissed in the 18th over, India still required 15 runs from 14 balls before their final over stutter with just seven runs required.
Axar Patel was caught and bowled by Sean Abbott for two, and Ravi Bishnoi and Arshdeep Singh were run out attempting to get Rinku back on strike.
Rinku was not in India's World Cup squad but finished with 22 from 14 balls to steer India from chaos to victory, even if his last-ball six was ultimately irrelevant.
Australia rested World Cup winners Glenn Maxwell, Adam Zampa and Travis Head for this game but they are part of the squad in India, while the rest of the one-day international squad including captain Pat Cummins have returned home.
India, meanwhile, have rested most of their World Cup squad but batter Shreyas Iyer is expected to return for the final three matches.
The series continues on Sunday, 26 November in Thiruvananthapuram.
