Set a challenging target of 167 after South Africa opted to bat first, India were off to a blazing start with the opening duo of Shafali and Sehrawat adding 77 runs in just seven overs at Willowmoore Park.
Shafali, who has already played 51 T20Is, 21 ODIs and two Test matches for the senior team at the international level, looked in excellent touch as she toyed with the South African bowlers and put her side on course for a big win.
While Shafali went after the bowlers from the word go, Sehrawat too maintained a very good strike rate throughout her innings, which came off 57 balls and included as many as 20 boundaries.
However, having smashed nine fours and a six in an entertaining stay, Shafali was dismissed by off-spinner Miane Smit at the start of the eighth over. Her strike rate was an incredible 281.25 when she got out.
This was after the Indian captain also shone with the ball, picking up two wickets to put the brakes on the South African scoring rate. Shafali bowled her full quota of four overs and returned with impressive figures of 2/31.
Unperturbed by the departure of Shafali, Sehrawat carried on in same vein and helped her team cross the line with 21 balls to spare. Sehrawat's previous best was 40 against the same opponents.
Earlier, the South Africans too got a flying start with Simone Lourens (61 off 44 balls) and Elandri Janse van Rensburg (23 off 13) putting on 56 runs in only 4 overs.
Left-arm spinner Sonam Yadav gave India their first breakthrough when she had Rensburg caught behind by Richa Ghosh, who is also a senior India player.
Shafali, then, got into the act by dismissing her counterpart Oluhle Siyo for a duck.
Madison Landsman chipped in with 32 off 17 balls, while Karabo Meso and Miane Smit made brisk 19 and 16, respectively.
However, the home team was pegged back after top-scorer Lourens was run out in the 17th over, a crucial juncture, as they settled for 166 for five.