Japan is the birthplace of the Olympic sport of judo and the Japanese are by far the most successful team in its history but they will face a strong challenge from France in London.

Since judo became an Olympic sport, Japan have won 35 gold medals compared to 10 from the next best country, France.

In the World Championships they have won more than twice as many medals as second placed France and more than three times as many as third place South Korea.

But France is the home of the biggest star in judo, five-time heavyweight world champion Teddy Riner, who is chasing his first Olympic title.

They also have three women's world champions in Gevrise Emane (-63kg), Lucie Decosse (-70kg) and Audrey Tcheumeo (-78kg).

But Japan, who almost always top the medal table, are the only country that can field a competitor capable of winning in every weight division.

Yet, while they can field two fighters per weight at the worlds, they can only pick one at the Games.

Japan will likely dominate the women's lighter divisions but selectors face a tough choice between world champions Misato Nakamura (-52kg) and Aiko Sato (-57kg) or the respective world number one's in Yuka Nishida (-52kg) and Kaori Matsumoto (-57kg).

At under-48kg the choice is perhaps slightly easier as Haruna Asami is number one and the twice reigning world champion, although Tomoko Fukumi is the number two and former world champion.

The best female hope for the French is Decosse, not least because she is the star of the women's team and widely considered, even by the Japanese, as the best women's fighter on the circuit.

A three-time world champion and four-time European champion she was beaten in the Beijing Olympic final by long-time rival Ayumi Tanimoto and is now looking to make amends.

That won't be easy, though, as Japan's Haruka Tachimoto beat her, albeit narrowly, in the Paris Grand Slam final in February.

Emane has a wonderful record with two world titles and four Europeans but she faces world number one Yoshi Ueno of Japan, herself a twice world champion.

Riner, however, will clearly be the biggest draw in London and an undisputed favourite.

Japan's 1984 Olympic champion and a legend of the sport Yasuhiro Yamashita said after last year's world championships: "Teddy Riner is a wall. Before these worlds the Japanese didn't realise that.

"They still thought they could beat him but now they know it's impossible. After London he will be a superstar."

Yamashita said only illness or injury could prevent Riner from winning and it is hard to argue otherwise.

Elsewhere in the men's divisions, Uzbekistan's Rishod Sobirov is so far ahead of the competition at under-60kg that he actually has twice as many world ranking points as his nearest challenger.

While many would automatically think Riner is the most dominant favourite in any division, the reigning twice world champion Sobirov is at least on the same level.

Russia has the top two in the world at under-66kg in Alim Gadanov and Musa Mogushkov, but only one can go, while Maxim Rakov of Kazakhstan is the world number one and favourite at under-100kg.

The men's under-90kg division will be a real highlight with current world champion and popular Georgian-born star Ilias Iliadis of Greece, who's real name is Jargi Zviadauri, taking on some tough opponents.

The Japanese have the second, third and fourth ranked fighters but only one will go, perhaps Daiki Nishiyama, but Georgia's Varlam Liparteliani and Brazil's Tiago Camilo should also be in the mix.

The men's under-81kg is always a competitive division with Brazil's Leandro Guilheiro, world champion Kim Jae-Bum of South Korea, German Olympic champion Ole Bischof and Olympic under-73kg champion Elnur Mammadli of Azerbaijan making up one of the toughest draws.