Long before the race began vantage points along the winding hill between Ipanema and Copacabana had been filled with bodies and dangling legs.

On the stretch of sand that runs in the shape of a question mark along Avenidas Atlantica tens of thousands lined up for one of the best attended events of the Games, the free men’s Triathlon on Copacabana Breach.

Britain’s Brownlee bothers Alistair and Jonathan were the hot pre race favourites but the promised rain in Rio didn’t arrive. Instead blistering sunshine hammered down with temperatures above 30 degrees.

But still it became a family procession, a celebration of a unique pair of siblings and a race that was never in doubt from the moment the brothers ran up the short stretch of sand from the Atlantic Ocean swim.

Almost side by side in the leading group that dragged themselves from the water across the deep sand to fetch their bikes, that’s how they began and that’s how they finished.

The brothers held that formation until the third lap of the running leg when the holder Alistair decided he needed a firmer grip on his second triathlon gold medal.

Not for a moment was their dominance and grip on the race in doubt. The question was which of the two brothers would win. In the past and especially around Hyde Park four years ago that rivalry favoured 28-year-old Alistair. And so it was.

His lead up the Copacabana strip at the end was so comfortably held that 50 metres out he snatched a Union Jack from the crowd. Glancing back he could see his brother and with the finish line in sight was able to enjoy the final few stress free seconds.

These have been the most testing of four years for the older brother. Every season was a new injury, every season another doubt that he could ever stay fit for long enough to hit his peak once again.

In the end he fell over the line in 1:36.32 glistening and parched in the heat haze. Six seconds later Jonathan joined him, also falling on the blue carpet in equal measure celebrating and exhausted.

History was made with Alistair the first to successfully defend an Olympic Triathlon title and 26-year-old Jonathan turning his bronze from London into silver. Henri Shoeman from South Africa, who stuck with the two throughout the race claimed bronze ahead of Frenchman Vincent Luis.

“Unstoppable in the swim. Smashed the bike and powerful in the run. You won’t see the likes of them again,” said Australian Aaron Royle. “They are super strong and that’s the way they race.”

Ireland’s interest Bryan Keane came over the line in 40th position in the brutal conditions. Many athletes, beaten and dehydrated by almost two hours out on the tough course, were doused in cold water and taken from the finish line in wheelchairs.

Keane, who was poised to qualify for the London Olympics but shattered his knee cap after being hit by a car while out cycling his bike in 2010, came in with a time that was +7.08 minutes behind the winner in 1:52.09.

The Cork Triathlete wasn’t helped in that number by his transition from the sea swim to the bike. He lost time fumbling to clip his helmet in place before taking off on the hilly track.

Keane came out of the 1500m open water swim around Copacabana Beach 52 seconds behind the leaders and was unable to close that gap. Instead it increased.

By the time he ran into the transition area after the eight lap, 40k cycle he trailed the leaders, a group of 10 riders, by almost five minutes, a time he would unlikely make up in the 10k run, a circuit up and down the beach front.

But it was the Brownlee brothers who set the early pace with a group of eight other bike riders and they quickly put distance between the rest of the group. Shouts of “you’re not working hard enough,” could be clearly heard as they passed through the transition zone after each lap suggesting the group were working together to open the gap.

“I was pretty confident we would get first and second but I didn’t know which way round it would be,” said Alistair.

“I just had the edge on Jonny but he has killed me in training and I have been going through hell. It has been so hard. I have woken up in pain every day.

“The swim wasn’t that quick but we knew the first two laps on the bike would be crucial. The last few weeks we have been training to commit and, boy, we did. As soon as we got to halfway I knew we were going to get two medals and it was just a run for it.”

After a clean exchange of their bikes for running shoes, the two quickly burned off their rivals and had soon built up a six second lead on Vincent and Shoeman.

It was then the sibling psychology kicked in with the two out on their own and really only racing each other for the gold medal. But any thoughts of a brotherly gesture from Alistair, who had already won gold was quickly forgotten. He invisibly lifted the tempo and Jonathan couldn’t respond. It was a one, two, even better than their run around the Serpentine in Hyde Park.