Eoin Morgan hailed "phenomenal" Jos Buttler for setting up a series-opening win for England with his fourth one-day international hundred.
Buttler's century, his second in as many ODI innings, was his slowest to date - a statistic, given it came from only 73 balls, which says much about his outstanding ability.
It was enough too, along with three other England 50s, to give them the edge in a high-scoring match eventually settled in their favour by 39 runs on Duckworth/Lewis.
Quinton de Kock had returned fire with a career-best 138 not out but then an evening storm stopped South Africa in their tracks on 250 for five in pursuit of 399 for nine.
England's second-highest ODI total, and their biggest away from home, owed most to Buttler (105) - with Alex Hales (57), Joe Root (52) and Ben Stokes (57) all contributing signficantly too.
Captain Morgan said: "Jos was phenomenal. He is someone who can certainly change the game. It was an unbelievable effort, and great to watch.
"We're very lucky to see it at training all the time, but to see him do it in the last game of the UAE and the first here really sets up the series.
"He does put a lot of pressure on himself, because he has a huge amount of ability, but it really does set up what I hope is a great series for him."
Morgan was confident England were on top when the rain came at the Mangaung Oval.
"You'd take 399 every day - it was a monumental effort," he said.
"The tone was set by the two openers and continued right down the innings.
"Doing that in the first game of the series is really important.
"Re-engaging with the type of cricket we have played after a little bit of a break is very important for the team.
"We have players who really enjoy playing in that vein, so it's really exciting."
Morgan's opposite number AB de Villiers blamed himself for getting out for just eight - one of the wickets he felt South Africa could not afford to lose, in support of De Kock.
"We lost a couple of wickets too many, so I think it was advantage England," he said.
"But our run-rate was right up there, and I think we gave them a nice scare and showed them what we're all about as a top seven."
Stokes' brilliant catch on the long-on boundary will live long in the memory - and in some partisan South African minds, there will be just a little doubt attached too as to its authenticity too.
Suggestions arose that the boundary rope had previously been shifted back, and therefore allowed Stokes to complete the catch without taking the ball out.
But there appeared to be a note of minor mischief to De Villiers' recollections.
"It was a great catch, and I thought he did well to keep it in ... if he did!
"There are lots of rumours and theories going on in the changing room.
"I'm not getting involved, but a lot of guys think I was a bit unlucky there.
"I'm happy to walk off when the umpire gives me out."
In any case, De Villiers admitted he made his own trouble.
"I used my feet a little bit too well and got too close to the pitch, so I couldn't get enough elevation on it.
"I did try to get it a bit squarer, so I was a bit unlucky that the wind pushed it a little bit closer to him.
"It was a silly shot. I'm better than that. I blame myself."