Morgan was disappointed to have lost the match, and said: "We seemed to nick everything, South Africa made the most of the conditions, but we've had better starts than 20 for 6".
South Africa may not have won an worldwide trophy for almost two decades but they go into the ICC Champions Trophy 2017 as one of the favorites for the title.
England on the other hand maintained a psychological advantage heading into the ICC Champions Trophy winning the series 2-1.
Shocked into a change of mindset by their wretched from in the tournament, they discarded their coach, several senior players (including their top wicket-taker, James Anderson, and top run-scorer, Ian Bell) and their old approach in reinventing themselves as an ultra-aggressive side who are committed to attacking with bat and ball as a default option. Only Joe Root was to buck the trend when he was dismissed by two after Wayne Parnell trapped him LBW.
Despite, the convincing victory, it is England, who claimed the series 2-1 following their wins in the first two games. "There was something there for the bowlers today that all of us could capitalise", said Rabada.
Jake Ball was bowled by the spinner, before Steven Finn chipped one up to De Villiers in the 32nd over.
"We have put in a lot this series but this was a hiccup", Morgan said.
Sebastien Bourdais undergoes surgery after Indy qualifying crash
Bourdais released a statement through his team while recovering at Indiana University Health Methodist Hospital on Sunday. Asked about morale within the team , Coyne said: "Everyone's sad because we all know how good this year could have been".
Amla struck 55 off 54 balls with 11 fours and also reached the milestone of the quickest to 7000 runs in ODs - in 150 matches.
Roland-Jones - one of four players to come into the home side's starting XI - picked up his maiden global wicket when Hashim Amla (55 off 54 balls) dragged on, shortly after becoming the fastest player to score 7,000 ODI runs (153 matches).
England's chastening seven-wicket defeat against South Africa leaves them with questions to answer, and captain Eoin Morgan hoping confidence is intact for the start of the Champions Trophy.
That was the end of the foyrth over and next ball Alex Hales, trying to drive Rabada, got an outside edge to Amla and England were 15 for four.
The good news for England is that they can expect much more batting-friendly conditions on the grounds used for their Champions Trophy game.
Earlier, England crumbled against Rabada and Parnell.
Jos Buttler and Adil Rashid fell to consecutive deliveries by Rabada in the fifth over - both to catches by Faf du Plessis at second slip - but Bairstow survived the hat-trick ball.
However, he failed to build on it as he was stumped by Quinton de Kock off the bowling of Keshav Maharaj for 51, which came off 67 balls and included eight boundaries.