Fourth T20 international, DP World Wanderers, Johannesburg
India 283-1 (20 overs): Varma 120* (47), Samson 109* (56)
South Africa 148 (18.2 overs): Stubbs 43 (29); Arshdeep 3-20
India won by 135 runs; win series 3-1
Sanju Samson and Tilak Varma hit unbeaten centuries to lead India to a 135-run thrashing of South Africa in Johannesburg and a 3-1 T20 series victory.
Samson struck 109 off 56 balls and Varma smashed 120 off 47 in a staggering unbroken stand of 210 for the second wicket as India posted 283-1.
It is the first time two team-mates have scored centuries in the same innings of a men's T20 international between full member nations.
South Africa were bowled out for 148 off 18.2 overs in reply, with Arshdeep Singh taking 3-20.
Left-hander Varma crashed nine fours and 10 sixes after joining Samson at 73-1 in the sixth over, following the dismissal of Abhishek Sharma for 36 off 18.
Having made an unbeaten 107 in the third T20, Varma is the second Indian and only fifth batter overall to hit centuries in consecutive men's T20 internationals.
Wicketkeeper Samson was the first Indian to achieve the feat by smacking 107 in the opening T20 of this series.
In the fourth and final T20 at Wanderers Stadium, Samson hit six fours and nine sixes.
His partnership of 210 with Varma is the sixth highest in all men's T20 internationals, the highest for the second wicket and highest for India.
India's 283-1 is their second-highest total in men's T20 internationals, after making 297-6 against Bangladesh in October.
Varma reached his ton off just 41 balls, making it the third-quickest century by an India batter in men's T20 internationals after Rohit Sharma (35 balls against Sri Lanka in 2017) and Samson (40 balls against Bangladesh in October).
South Africa slumped to 10-4 in reply before Tristan Stubbs struck 43 off 29, but the Proteas still fell to their heaviest T20 international defeat by runs.