Curran, the Surrey fast bowler who was born in Cape Town, took three for 33 on debut to help restrict South Africa to 174 for eight.
The third match of the series is to be played in Cardiff on Sunday 25 June, with tickets available to purchase HERE.
Dane Paterson picked up four in this late collapse with Livingstone, the man Morgan had benevolently reprieved, following Billings when a ramp shot, first ball, met fresh air and middle stump was clattered.
Eoin Morgan's men were asked to chase down South Africa's 174 for eight after Surrey seamer Tom Curran had become the fifth England player to take three wickets on his worldwide T20 debut.
South Africa also made three changes in a match they had to win to keep the three-match series alive.
Even though the Proteas began to lose wickets in a hurry after De Villiers' departure, Farhaan Behardien's quickfire 32 enabled them to finish on 174/8 off their 20 overs.
That dismissal in the eighth over, the tourists now 57 for two, brought De Villiers to the crease.
"We've been so good over the last 18 months and we just lost the game at the wrong time".
The first T20I was won by England by 9 wickets courtesy Jonny Bairstow's explosive 60. The decider is expected to be full of surprises and it will be an uphill task for South Africa to win today's game, hence clinching the series.
De Villiers had made a relatively pedestrian half-century in Southampton. They eventually fell short on 162 for seven.
Curran then had all-rounder Chris Morris caught in the deep off a slower ball. He claimed two more wickets in that spell, with Morris mishitting a slower-ball to long-on and Phehlukwayo bowled first delivery by a searing yorker.
England lost Sam Billings, opening in place of Hales, in the second over of their reply, the Kent player caught close in after failing to get hold of Morris. Jos Buttler (wk), 6.
Phehlukwayo was given the responsibility of the final over and he bowled magnificently, going for three singles from his first three balls before Liam Livingstone was ran-out after a mix-up. As it was, Dawson was required to hit another four (or three to ensure a Super Over) and was unable to make contact with his heave.