A couple of miscues could have gone to hand, not ground, and he was dropped, a skier at cover in the 18th over by Justin Ontong. But there were plenty of rasping shots in his 42-ball innings to remind of his quality, before his eventual mad moment.
Young quick Marchant de Lange delivered the final over when both Nathan McCullum and Doug Bracewell holed out and Tim Southee, needing a six off the final ball, could only manage a swing and miss.
"When you look at where we were in the game and where we ended up, I guess we faltered," McCullum said, not calling it a choke, but not actually denying it either.
"We came under pressure and didn't measure up. Use whatever words you want but we didn't get the job done. It's bitterly disappointing."
McCullum did not point the finger at a "distraught" Ryder for the tumble - others could have finished the task, he said.
But when calm heads and sensible strokes were all that was needed, things went badly awry.
South African skipper AB de Villiers was chuffed his players retained belief to the end. "I kept telling the boys, 'Keep your standards, keep believing. There is no room for giving up,' and we didn't tonight."
It was a cruel end because New Zealand had this game well in hand until the final overs.
Openers Rob Nicol and Martin Guptill made a flying start, as if they had urgent business elsewhere. McCullum and Ryder kept things ticking over and kept New Zealand well in front in comparative terms until the dramatic late slip.
The key chunk of the South African innings was a 24-ball spell during which the visitors lost four for 17, covering the last ball of the 13th over through to the 17th.
Mark that down to fine bowling from Bracewell and Southee - both did a top job - and offspinner Nicol.
Sometimes you get an innings where a player can't stay out of the action. Last night it was Nicol, who had a hand in five of the seven dismissals.
He took two catches, and two wickets, and ran out the threatening J-P Duminy with a slick piece of work.
Duminy's was the eye-catching hand of the South African innings, 38 off 20 balls.
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