If Alistair Brownlee holds on to win he will be the first triathlete ever to win two Olympic golds. 

The other athlete who came close was Canadian Simon Whitfield -a silver medallist at Beijing 2008 and ITU legend.

Alistair Brownlee kicks and kicks hard.

The elder brother decides this is the time to take the race by the scruff and assert himself on his younger sibling.

And Jonny cannot match that spurt of pace!

A gap of five, six, seven seconds is growing all the time.

Alistair and Jonny Brownlee pass through halfway in the 10km run, seven seconds ahead of South African Henri Schoeman in third.

Mario Mola is not making an inroads into the brothers - the Spaniard is still more a minute adrift.

Annie Emmerson
BBC Sport triathlon expert & former GB triathlete

Barring a disaster we are going to see the Brownlee brothers on the podium again.

Henri Shoeman is alone in third now.

But he is racing in glorious isolation with the Brownlee brothers a speck in the distance.

Alistair Brownlee is letting Jonny set the pace, stalking and waiting, as they approach the halfway point of the 10km run stage.

Annie Emmerson
BBC Sport triathlon expert & former GB triathlete

The crucial part for the Brownlees here is not to overheat.

They are both running very intelligently.

Nick Howes: Downing tools to watch the triathlon. These guys are seriously impressive

Lou Smith MA: The Brownlee brothers are machineeeeees!

Luke: Waving my imaginary #GBR flag. The Brownlee brothers are running away with it. No pun intended.

This is a family affair now.

Alistair, 28, leads the head-to-head against Jonny, 26, by 16 races to seven.

Elder sibling priority again? Or time for Jonny to upset the kitchen table and the odds?

Alistair and Jonny Brownlee have left France's Vincent Luis behind them.

The Frenchman is six seconds adrift as the brothers go through 2.5km of the 10km run leg.

The South African Henri Shoeman is seven seconds behind and might be a stronger contender for the podium.

Annie Emmerson
BBC Sport triathlon expert & former GB triathlete

It is interesting to see how the Brownlees are starting out on this run.

We are used to see Alistair flying out but at the moment it's conservative - in my view sensible. 

After a tough, tough bike ride, when you are over a minute ahead of Mola, you can afford to warm yourself into this run.

Spain's Mario Mola is through transition, but he has a whopping one minute and 20 seconds to make up on the leading Brownlees and Vincent Luis.

The 10km run is his strongest element, but it will need to be an absolutely blistering run to overhaul the Yorkshire duo.

Aimee Lewis
BBC Sport in Rio

Republic of Ireland flags are on display and are being rigorously waved as Thomas Barr breaks the national record in finishing fourth in the men's 400m hurdles final.

Ireland fans next to me had their head in their hands as they awaited the result but soon celebrated, shouting "well done, Thomas" when they learned it was a record-breaking run. In fact, they're still shouting. 

Image source, .

Image source, .

Image source, BBc

The lead group unclip, swing their legs off the frame and scoot into transition.

Neither Alistair or Jonny Brownlee have any problems with the fancy dress element and they and France's Vincent Luis have already broken free of the rest.

Just these three now. 

It looks like the identity of the medal winners has been been decided. 

The order is the only thing to be shaken down now.

GB Men's 4x100m relay team are through to the final after qualifying as one of the fastest losers.

The lead group - with both Alistair and Jonny Brownlee calling the shots and issuing the orders - take the bell for the final lap with a lead of a minute and 15 seconds on the rest.

Mario Mola back in the main group appears to have banked everything on a stonking run. He has hidden in the pack, saving his legs for a death-or-glory final leg.