Usain Bolt takes the second step towards sporting immortality in Rio and the iconic district of Copacabana is the battlefield for the remarkable Brownlee brothers at the Olympics on Thursday.

Bolt moved seamlessly into the 200m final (2230 local time, 0130GMT), the sprinting superstar cruising through Wednesday night's semis.

Justin Gatlin, who ran Bolt closest in the 100m on Sunday, failed to make it out of his semi.

If Bolt triumphs that will leave him requiring a win in Saturday's 4x100m relay to achieve the 'triple triple' of sprint titles from the 2008, 2012 and 2016 Games.

The 200m is one of 26 medals on the table as Rio approaches the home straight with only four days of the first Games to be staged in South America remaining.

The men's 400m hurdles includes Ireland's Thomas Barr who was so surprised by his semi-final win asked endearingly: "When is the final?!"

There are also gold medals on offer in men's shotput and women's javelin and the decathlon.

US star Ashton Eaton leads Germany's Kai Kazmirek going into the five concluding legs of the decathlon -- 110m hurdles, discus, pole vault, javelin and 1500m.

At 2359 local time a whistle will be blown on Copacabana beach to signal the start of the men's beach volleyball final.

The midnight match sees hosts Brazil up against Italy.

Earlier, nearby Fort Copacabana will be the setting for the latest battle between British siblings Alistair and Jonny Brownlee in the triathlon.

Alistair struck gold in London 2012, with Jonny, two years younger, claiming bronze.

In the boxing ring, Julio Caesar La Cruz is trying to complete Cuba's Olympic gold medal set. 

Cuba have won gold in every category, except light heavyweight. Standing in La Cruz's way is Kazakh Adilbek Niyazymbetov.

It's a hectic day on the water with four finals at the canoeing and another four in sailing after two regattas had to be held over from Wednesday.

In the pool, Russia are out to continue their total domination of synchronised swimming stretching back to the Sydney 2000 Games in the team contest.

And it's the women's 10m platform diving final.

Up at the Deodoro military camp, Argentina and Belgium clash in the men's hockey final, both countries having their first shot at Olympic gold.

There are also golds to be had in women's wrestling and taekwondo. 

At the badminton it's Japan v Denmark in the women's doubles final.

And at the basketball, in women's semi-final action, Spain face Serbia and France take on the USA.

And world number two Ariya Jutanugarn of Thailand tops the women's Olympic golf leaderboard going into the second round.

Source: AFP