De Klerk smashed an unbeaten 84 off just 54 balls to steer South Africa to their target of 252 with seven balls to spare.
It was a remarkable turnaround after the visitors had slumped to 81-5 inside 20 overs.
Key contributions from captain Laura Wolvaardt (70) and Chloe Tryon (49) helped lay the platform before De Klerk sealed the result with a flurry of boundaries.
India had earlier posted 252 thanks to a superb 94 from Richa Ghosh, but it wasn’t enough as they suffered their first defeat of the tournament.
After a delayed start, India made a solid beginning with openers Smriti Mandhana and Harleen Deol, but Masabata Klaas struck twice to leave them 83-2 in the 17th over.
Tumi Sekhukhune and Tryon then ripped through the middle order, claiming crucial wickets including Jemimah Rodrigues and captain Harmanpreet Kaur.
Ghosh led the fightback, reaching a fluent fifty and dominating the death overs alongside Sneh Rana (33). Their 88-run stand helped India recover from 92-5 to a competitive total. Ghosh was eventually dismissed for 94 off 77 balls.
South Africa’s reply started badly as Tamzin Brits fell for a duck and Suné Luus for five. Wolvaardt held the innings together with a composed 70 off 111 balls, but wickets continued to fall at regular intervals.
Tryon injected momentum with a brisk 49, and when she was trapped lbw by Rana, De Klerk took charge. She unleashed a series of powerful strokes, including back-to-back sixes off Gaud in the 47th over, to turn the game decisively in South Africa’s favour.
She finished the job in style, launching her fifth six to clinch a memorable win for the Proteas.
The Proteas Women now have two wins from three matches in the tournament and will next face Bangladesh on Monday in Visakhapatnam.
Photo: Pankaj Nangia/Getty Images
