With Great Britain brothers Alistair and Jonny Brownlee the favourites to take gold and silver in the men's race, some thought they may try to cross the line together.
But the women beat them to it, with Nicola Spirig of Switzerland and Sweden's Lisa Norden breaking the tape at the same time in the closest finish in Olympic Triathlon history.
Officials needed a photo to split the pair, who were given exactly the same time. Spirig climbed to the top step of the podium to collect the gold medal, her first Olympic title at her third Games.
Norden took silver, while Australia's Erin Densham won bronze three years after she feared her life was in danger because of heart problems.
USA's Sarah Groff had performed a near miracle to get back to the leaders on the final kilometre of the run but she was left in the most frustrating position of all, fourth.
The finish may have been a shock but the protagonists were not, with Spirig and Densham both having won two World Series races this season while Norden is a frequent visitor to the podium.
It was a similar story in the men's Triathlon, where Alistair Brownlee put to bed the much-repeated statistic that a favourite had never won Olympic gold.
The 24-year-old has dominated the sport with a series of phenomenal performances over the last three years, and it was no different in London.
Brownlee's time for the 10km run was only 1:37 slower than the time his countryman Mo Farah ran to win the 10,000m in the Olympic Stadium.
The only slight surprise was that his younger brother did not manage silver, the 22-year-old instead taking bronze.
He was not helped by a 15-second penalty for jumping on his bike too early but admitted he would not have caught silver medallist Javier Gomez anyway.
The Spaniard is a two-time world champion but had no answer to the speed of Alistair Brownlee, although his performance gave him hope that the world and Olympic champion is within reach.
The 29-year-old said: "I was closer but when he is fit he is really hard to beat. You need to do everything perfect but experience tells me there is no-one unbeatable."