The world's number one team lost the last eight wickets for 51 runs after being comfortably placed at 116 for one at one stage.
Captain AB de Villiers, on 16, perished trying to pinch a quick single and David Miller (one) was dismissed in farcical circumstances with both batsmen stranded at the same end to leave South Africa struggling at 142 for four.
Hashim Amla was very watchful, escaping an early run-out attempt as he toiled for runs before falling for 35 off 54 balls. We never got going and it's very sad We were hoping to play better but we came unstuck against a better team.
De Kock grinded onto an efficient if unspectacular half century before Jadeja hit the opener's off stump.
De Villiers, who took over as South Africa's limited-overs captain back in 2011, doesn't a have a good captaincy record in ICC events. Read Also: England, Bangladesh fans look for semi-final tickets as Indians hold them " Today, those key moments in the game where you look for someone to take the initiative just seemed to pass South Africa by. After Bhuvneshwar Kumar and Jasprit Bumrah kept it tight with the new ball, it was Ashwin, who kept up the pressure that led to the South African batsmen taking that extra risk and giving away their wickets.
Faf du Plessis said the label of chokers doesn't haunt them and termed the loss against India to poor performance.
Monday's match had the look of a "dead rubber" after both sides were beaten first up, with Pakistan suffering a 124-run thrashing by arch-rivals India. Rohit Sharma then put his foot down to score runs in the way India would prefer, sending an on-drive for four before a six off the next of Rabada's deliveries.
"It s more enjoyable for myself and also it s working for the team. No one has ever had any doubts over the ability that he possesses to win games for the country, and he's done it in big tournaments", Kholi said.
South Africa responded with back-to-back maiden overs but consecutive boundaries for Dhawan just about kept India on course.
Virat Kohli's decision to field first on a flat Oval track on a bright and sunny London day was a result of the nature of the match and perhaps a lingering memory of their defeat at the hands of Sri Lanka on Thursday last. It is important to grab those opportunities. "I can take this team forward".
"We are indeed fortunate in the quality of our team leaders, and Farhaan remains very much part of this group".