Rio Olympics 2016: Games set for opening ceremony

The build-up has been dominated by a Russian doping scandal, the Zika virus and issues with the city's security, infrastructure and venues.

But it is time for the sporting action to take centre stage.

These are the Games of the 31st Olympiad but are the 28th to be held as those in 1916, 1940 and 1944 did not take place because of war.

When does it start?

The Games - held in South America for the first time - officially take place between 5 and 21 August, but they have actually already started.

The opening ceremony is at midnight BST on Friday night but the action kicked off two days ago with the women's football.

Defending Olympic men's tennis champion Andy Murray will be Great Britain's flag bearer inside Rio's Maracana stadium on Friday.

An estimated three billion people will watch the ceremony, which has taken five years to produce and includes 300 dancers, 5,000 volunteers and 12,000 costumes.

Brazilian supermodel Gisele Bundchen and Briton Dame Judi Dench are confirmed to have roles in the production before the 207 competing teams take part in the Parade of Nations.

Who is taking part?

There will be 10,500 athletes from a record 207 teams competing in Rio, including the Refugee Olympic Team, while it will be the first time Kosovo and South Sudan have taken part in the Games.

The Refugee Olympic Team will compete under the Olympic flag and has 10 members - five from South Sudan, two from Syria, two from DR Congo and one from Ethiopia.

With 554 athletes, the United States has the largest Olympic team, but 100m runner Etimoni Timuani is the only athlete from the South Pacific nation of Tuvalu.

The Rio Games will be the first to feature Olympians born since the year 2000 - and the youngest is 13-year-old Nepalese swimmer Gaurika Singh.

But what about the actual sport? 

Competitions will take place across 32 venues in Rio, with football matches also scheduled for the cities of Belo Horizonte, Brasilia, Manaus, Salvador and Sao Paulo.

There are 306 events in 28 Olympic sports but none are bigger than the 100m sprint final and the world's fastest man Usain Bolt.

The Jamaican is aiming for an unprecedented triple triple, as he tries to win the 100m, 200m and 4x100m relay titles for the third time - and his battle with American sprinter Justin Gatlin is likely to be a highlight of the Games.

USA swimmer Michael Phelps, the most decorated Olympian of all time, will be looking to add to his 18 gold medals.

American tennis player Serena Williams could win her fifth Olympic medal, while Team USA's star-studded basketball team will be aiming for their third consecutive gold.

Brazil's Barcelona striker Neymar will once again carry the hopes of the home nation as they go for gold in the men's football.

Among those who miss out are top tennis players Roger Federer and Stan Wawrinka, NBA stars Stephen Curry and LeBron James and a number of golfers.

Anything new?

Rio marks the return of golf and rugby to the Olympics.

Golf is returning after a 112-year absence but without more than 20 of its top players.

The top four male golfers Jason Day, Jordan Spieth, Rory McIlroy and Dustin Johnson have all withdrawn because of Zika fears.

In fact, only four of the top 10 will be in Rio - and McIlroy said he probably will not even watch television coverage of golf at the Games, preferring "track and field, swimming, diving, the stuff that matters".

Rugby sevens will be making its debut at the Olympics, although rugby union featured regularly at the Games until 1924.

Read more at BBC