It was an over sent from the heavens. Three googlies from Imran Tahir and nearly three wickets.
Marlon Samuels looked to drive the first one through the covers. The ball turned into him and forced him to hit it straighter, and in the air. Tahir got his left hand to the ball but couldn't wrap his fingers around it.
Andre Russell looked to slog the second beyond wide long-on, but ended up hitting it squarer than intended and deep midwicket ran a few steps to his left to take a simple catch. Darren Sammy simply didn't pick the last one. It hung deliciously over his eyeline, dipped wickedly, and turned through the gap between front pad and airy cover drive to hit the top of middle stump.
Two wickets taken, only one run conceded and West Indies were 100 for 6 after 17 overs. The over might have turned the match South Africa's way had West Indies been chasing 140. But they were only chasing 123 and still only needed a perfectly gettable 23 off the last three overs.
After the match, South Africa captain Faf du Plessis was quite clear in his assessment that his side fell at least 10 runs short of a defendable total.
"The batting today was the difference between us winning and losing," he said. "We needed to get to 130-135 to have a par score. I thought we were 10 runs short, definitely."
On the eve of the match, du Plessis had counted adaptability and "being smart in decision-making" among the strengths of his batting side. He had hoped these qualities would make the difference against a West Indies batting unit reliant on power hitting, given the large outfield and the expectation that the pitch would provide turn.
The pitch met du Plessis' expectations: it was slow, low and offered a fair degree of turn, though not to the extent seen during the India-New Zealand match on March 15. West Indies' batting proved to be as reliant on big hitting as du Plessis had noted and, as a consequence, was not at its best with the ball not coming on to the bat.
But before they could expose West Indies' frailties with the bat, South Africa had failed to demonstrate the adaptability and smart decision-making du Plessis had spoken of. After the match, he conceded that they had been "frantic" at the start of their innings, when they lost their three most experienced batsmen to what he called "soft" dismissals: Hashim Amla to a run out, du Plessis himself to a spooned catch taken at mid-off, and AB de Villiers to a shot played across the line. Rilee Rossouw also slashed a wide delivery straight to point.
"Obviously batting first, the thinking was that it wasn't going to be the same wicket as Mumbai, doesn't take a brain surgeon to look at that. But those decisions you make when you're batting, we didn't make them tonight," du Plessis said. "The run-out, caught at mid-off, and Rilee - our first three wickets for me were all soft wickets. AB's wicket was also a soft wicket.
"They didn't bowl us out tonight. We were put in situations where we needed to be smarter and we weren't. If you don't do those things you're not going to bat as well as you can. We went into this game thinking that West Indies is a power hitting team and we rely on being smart. Ten or 15 runs more, I think we could have won the game. They don't rely on touch, on getting ones and twos, whereas this ground is spot on for that. That's where we lost the game."
Du Plessis said Quinton de Kock and David Wiese - who added 50 for the sixth wicket - showed South Africa how they could have played on the Nagpur surface, but only after the top order had already collapsed.
"I thought we were very frantic there, up front," du Plessis said. "Obviously you never want to start your innings with a run out, that just puts you back, puts it all, puts everything in a bit of a negative mode, because you're giving the opposition a wicket, but to lose three or four wickets so quickly, that broke our momentum in the innings, and that was the difference between us [scoring 122 and] getting to 140.
"The guys batted beautifully in the middle, David Wiese once again as a guy that's coming in today, had a great game, and I can't fault the bowlers today. Obviously there's been a lot of pressure and a lot of stuff said about our bowling unit over the last two weeks or so, but they fought really hard today.
"Especially in a big game like today, you want your big players to stand up, and myself, Hashim and AB, one of us needed to anchor the innings and be there. Quinton played an amazing innings, a mature innings, that's something he hasn't done a lot. Normally he plays his aggressive game and he's very free. Today the shoe was on the other foot and he adapted brilliantly. And he showed the rest of the batting unit what it is like to adapt on that wicket."
Despite all this, South Africa's bowlers kept them in the game till the last over. Tahir took those two wickets in the 17th and Wiese, mixing up his pace brilliantly, conceded only three runs in the 18th over. It took a slash and a thick edge past the keeper from Marlon Samuels, which streaked to the third man boundary in the 19th off Chris Morris, to bring the equation down to 10 off eight balls.
Du Plessis said the edged four made him think "oh my word, it's not meant to be for us today", but he was quick to add that West Indies had earned their luck by staying "half a step" ahead of South Africa right through the game.
"We're not playing close to how good we are or can be, and that's frustrating," du Plessis said. "We want to be better, and unfortunately we're not producing the goods on the day. As I said, you need a bit of luck but also you make your own luck, and I feel if you win those small moments in the game, generally the luck goes your way.
"That's why it didn't go our way tonight, because we were just half a step behind West Indies all the time. But they're playing great cricket and that's why it's going for them. They're a confident team and things will fall their way, because you almost earn that luck, and they deserve it."
The win put West Indies through to the semi-finals and left South Africa hanging from edge of the precipice. They will need Sri Lanka to beat England, and then need to beat Sri Lanka themselves, to have any chance of progressing. It was not the situation du Plessis had expected his team to be in at this stage of the competition.
"[I'm] disappointed, because I had strong hopes of winning the tournament, and now we're hoping for other performances to go our way," he said. "We'll obviously be rooting for some opposition to try and do us a favour, but if it doesn't happen like that, there's no excuses."

Karthik Krishnaswamy is a senior sub-editor at ESPNcricinfo