RIO DE JANEIRO - Japanese superstar Kohei Uchimura's bid to defend his all-around title and topple men's team holders China and US teen Simone Biles' quest for women's gold are set to highlight artistic gymnastics at the Rio Games.
Japan's Kohei Uchimura performs in the Men's Horizontal bar Final at the 2015 World Gymnastics Championship in Glasgow, Scotland, on November 1, 2015
Uchimura, 27, and Biles, 19, have dominated the four-year Olympic cycle since London and are overwhelming favourites to finish the Games with all-around gold.
Both will also be looking for further gold in the team and apparatus events in the Rio Olympic Arena from August 6.
'King Kohei', considered one of the greatest gymnasts ever, has not been beaten in the all-around since 2009, winning a sixth consecutive world all-around title in Glasgow last year.
He will be competing in his third Olympics in Rio where if he succeeds in defending the all-around title he won in London after taking silver in 2008 he would become the first man to do so since compatriot Sawao Kato in 1972.
Cuba's Manrique Larduet will be hoping to follow on his success in Scotland, where at 19 years he challenged the great Uchimura in the all-around to claim silver. China's Deng Shudi is the world bronze medallist.
In Brazil Uchimura has said his focus will be on claiming the only gold medal missing from his collection — the Olympic men's team gold.
China have won the last two Olympic men's titles having beating Japan in 2008 and 2012. But Uchimura helped break China's domination last year and end Japan's 37-year wait for the world title.
China's 12-year reign ended, as they slipped to third behind Great Britain, the 2012 Olympic bronze medallists, who are also hoping to thwart Uchimura.
China's Zhang Chenglong, a member of the gold medal winning team in 2012 saw the world defeat as "a warning for us before Rio".
Zhang, 27, has taken over as team leader from Zou Kai, a five-time Olympic gold medallist, who has retired. The four other team members -- Liu Yang, Lin Chaopan, You Hao and Deng -- are all making their Olympic debuts.
But Britain have been gaining confidence since Louis Smith's medal breakthrough on the pommel horse in Beijing.
"China and Japan have dominated for so many years," said Britain's Kristian Thomas. "We have laid down a marker that they are definitely beatable."
- Pushing the limits -
Biles's incredible journey could reach its pinnacle in Rio after becoming the first woman to win three consecutive all-around gold to take her tally to a record ten world women's titles last year in Glasgow.
The dynamic young Texan gymnast, who was adopted by her grandparents when she was a toddler as her mother struggled with drug and alcohol addiction, has pushed the limits of the sport and has not lost a competition in more than three years.
Small and powerful, Biles excels on the floor and the beam, and has proved unbeatable in the all-around where she won a duel in Glasgow with compatriot Gabby Douglas, the reigning Olympic champion, who took a two-year break and had to settle for world silver.
Biles arrives in Brazil full of confidence ahead of her first Olympics with five world medals - gold in the team, all-around, beam and floor and bronze on the vault.
Douglas, 20, the first black gymnast to win an Olympic gold in 2012, showed signs of weakness during US trials in July, having changed coach two weeks prior.
She nevertheless made the team to become the first reigning all-around gold medallist to return to the next Games since Nadia Comaneci in 1980.
Both Biles and Douglas will work together in a bid to keep the team gold in the US women's hands, after winning the world title in 2014 and 2015.
The five-woman US team also includes Madison Kocian, Laurie Hernandez and Aly Raisman -- the 2012 floor exercise gold medallist.
In London, Russia were runners-up to the United States and will be spearheaded by Aliya Mustafina, the bronze medallist in 2012. But Romania, bronze medallists in 2012, will not have a full women's team at the Olympics, having failed to qualify.
China, long dogged by allegations of fielding underage gymnasts, will be lead by Shang Chunsong, 20, also a challenger for the women's all-around title.
China won the women's team title for the first time in 2008 but finished off the podium in London.