By Peter Griffiths
LONDON (Reuters) - Russia's dominant Olympic wrestlers must overcome a youthful Iranian team, Japan's powerful women and a resurgent United States if they are to protect their traditional grip on the medals in London.
Russia topped the medals table four years ago in Beijing with six golds -- more than the next three countries combined -- and was well ahead of the pack in the previous two Games in Athens and Sydney.
However, their supremacy in one of the world's oldest sports looked to be slipping at the world championships in Turkey last year when Iran took four golds - the same as Russia.
It was Russia's lowest gold haul since the 2006 championships and their total of 10 medals was the worst since 2005, suggesting their rivals may have their best chance in years to catch up in London.
"There will be a greater spread of medals this time round in the male side of the sport," Shaun Morley, performance director of British Wrestling, told Reuters. Russia should still top the overall medals table, while Japan should dominate the women's events, he added.
Nearly 350 wrestlers will compete for 18 gold medals between August 5 and 12 at the vast ExCeL building, an exhibition center built on old docks next to the River Thames that has previously hosted boat shows, arms fairs and a G20 summit.
One of the original sports from the ancient Games, wrestling is an exciting mix of power, speed and technique.
There are two disciplines: Greco-Roman, where holds below the waist are banned; and freestyle, where competitors can target the legs. Men compete in both types, while women only take part in the freestyle.
After winning one bronze in Beijing, Iran should do better in London. They came second in the world championships and have huge talents in Mehdi Taghavi (freestyle, 66kg) and Reza Yazdani (freestyle, 96kg).
Japan, Belarus and Azerbaijan should be near the top of the medals table, while a reinvigorated United States will hope to improve on their single gold in Beijing. U.S. world champion Jordan Burroughs is among the favorites in the 74kg freestyle.
Among the others to watch are Russia's Besik Kudukhov, a four-times world champion who won bronze in Beijing in the 55kg freestyle.
A Greco-Roman highlight would be a rematch of the 2011 world championship (120kg) final between Turkey's Riza Kayaalp and Cuba's Mijain Lopez. The Cuban won gold in Beijing and had won four world titles before losing to Kayaalp.
One of the most outstanding female wrestlers is Japan's Saori Yoshida, chasing a hat-trick of golds after Olympic success in 2008 and 2004 in the 55kg division.
(Editing by Peter Rutherford)