Great Britain and China broke the world record in women's team sprint qualifying, then broke their own hearts with high-speed mistakes.
The British were disqualified and the Chinese were relegated from gold to silver after they botched their changeovers on day one of Olympic track cycling.
While the British immediately accepted their mistake, the Chinese were stunned.
Their French coach Daniel Morelon furiously argued with event officials, but to no avail.
British track legend Victoria Pendleton was in tears after she and Jessica Varnish won their first-round heat, only for officials to announce their disqualification.
"It was an illegal change. I came through in the change zone about a metre too early; we're talking about one hundredth of a second of a mistake there," Pendleton said.
"Jess moved up a fraction too early and I just saw the door and went for it, because that's my cue to try to squeeze underneath her as quickly as possible.
"It's one of those things that happens. It's quicker than a blink of an eye."
Their coach Dave Hunt ruefully added: At the end of the day that's four years hard work down the pan."
The circumstances surrounding the Chinese relegation were even worse.
After beating Germany in the final, the Chinese riders and their opponents were already talking to media when the announcement was made about the relegation.
"I really felt for the British team, I felt for the Chinese team," said Australian Anna Meares, who combined with Kaarle McCulloch for the bronze medal.
"It is part of it. You have to be technically on your game as well as physically."