World number 12 South Africa scored through Shelley Russell (4th minute), Pietie Coetzee (30th) and skipper Marsha Marescia (57th) to qualify for the London Olympics.
They remained unbeaten run in the tournament and had defeated India 5-2 in the league stage. India paid the price for their defence lapses and lack of finishing as South Africa rode on their better co-ordination, agility and solid defence to crush the hosts at their home ground.
India conceded an early goal in the fourth minute with Ritu Rani being the culprit as she failed to clear the ball from a back pass inside the D in the left flank, allowing Shelley Russell to steal it and comfortably slot it home.
Stung by the goal, India tried to attack from the left flank with Anuradha Devi Thokchom, who was back after missing two matches due to a hamstring injury, being in the action but they failed to penetrate the South African defence. The Indians crumbled under pressure as they fumbled with the ball and lacked co-ordination.
Even though they penetrated the rival camp, the hosts failed to build a single concrete attack. India earned their first penalty corner in the 10th minute but Sushila Chanu failed to stop the ball cleanly to squander the opportunity.