For Jim Hamilton that moment arrived in the 51st minute of Scotland's match against South Africa in Nelspruit's Mbombela Stadium last June. The shot in question was nothing more a gentle push on Springboks lock Eben Etzebeth, but its ramifications were far-reaching.
Referee Romain Poite, sensing the indignation of the crowd, consulted Gerry Coetzee, the South African television match official, for guidance on an incident that most observers thought was innocuous. Coetzee, who had already tried and failed to get a Scotland try chalked off, decided Hamilton deserved a yellow card, possibly the softest in the history of the game. Scotland, who had been leading before his departure, went on to lose 30-17.
The absurdity of it all was clear. Coetzee had all but handed victory to his countrymen on a plate. The International Rugby Board, who had extended the powers of the TMO just a few months earlier, are rarely quick at changing the rules, but in light of such a preposterous situation they were obliged to act. A few weeks later, and with little fanfare, they issued a diktat to the effect that TMOs at such significant games should be neutral. Talk about shutting the stable door after the horse has bolted.
Hamilton has every right to be furious about the incident, but he buried his anger long ago. "I don't think it was a sin binning," said the lock, "but I still feel that I let the side down a bit. I play on the edge, but I was very disappointed with the referee, and the way it happened.
"I'm not saying we would have gone on to win, but it was a massive contributory factor. The fact the team went down to 14 men against South Africa on their own territory was going to make things difficult. But we have to take encouragement from what went on before then."
By that, he means the display of devilment and self-belief Scotland, denuded by injuries after their loss to Samoa the previous weekend, delivered in the first half. When Alex Dunbar scored a try two minutes into the second period, Scotland found themselves 17-6 in front, with the prospect of a victory dangling before them. Coetzee's intervention put paid to that.
It was Hamilton's last involvement in Test rugby until he was named in Scott Johnson's autumn squad yesterday. With his wife Becky due to give birth within a few days, he had been given dispensation to fly home early. By the time the Scots had redeemed themselves with a 30-29 win against Italy in Pretoria, Hamilton was the proud father of baby Phoebe. And by the time the national squad landed in Edinburgh, the next phase of Hamilton's rugby career was already underway as he packed his bags and headed for pre-season training with Montpellier, his new club. Which is where he could be found the other day, generally content with the state of his game and with life in general.
"About four or five days after the birth I was back over here," said the giant lock. "That was tough, but it's what you have to do in this job. Since then, it's been a bit mixed. I played three pre-season games and then the first three league games, but I then picked up a knee injury so I was out for five weeks. It was a bit frustrating, but it's very rare to go through a year without an injury or two so you just get on with things. Then again, living in France has been fantastic. I'm trying to learn the language, and this is a great city. You're by the beach but you have the city, and it's an easy flight back."
Hamilton, now 30, could probably get by on sheer bulk alone, but the past couple of years have brought a renewed focus in terms of his thirst for self-improvement. As a consequence, his combination with Richie Gray has become Scotland's favoured second-row partnership, but he takes nothing for granted at a time when young Jonny Gray is starting to cast shadows almost as long as those of his elder brother.
"It has been great to see Glasgow going so well," he said. "I've been watching them and it's been good to see Jonny come through there. That's got to be excellent news for Scotland. The competition for places has got to be good for us all.
"Over here, I'm testing myself against top teams, physical teams, every week. As long as I keep myself really fit, I think it will develop my game. I really like the mixture of styles out here. There is a massive focus on the set piece, which is my bread-and-butter, but I am also looking to develop my game with more offloads and the French are renowned for that. It's great to be playing in a team with that range.
"The crowd are fantastic, too, and it is a great place to play. They have massive games here aga inst sides like Clermont, Toulon, Toulouse and Stade Francais."