The well-muscled men face off in the middle of a grassy field, as a crowd of thousands looks on eagerly. Slowly, methodically, they cover their chests and legs with olive oil -- first with the right hand, then with the left. Then they take turns oiling each others' backs.

Then the fun begins: Turkey's annual Kirkpinar festival, the highlight of the Turkish sporting calendar, is a three-day orgy of oil wrestling. Known as "yagli gures" (pronounced "yaw-luh gresh"), the slippery sport is considered by some to be the Turkish national game.

Oil wrestling season lasts eight months a year in Turkey, but all the local and regional matches are just warm-ups for the main event: the Kirkpinar in Edirne, the granddaddy of all oil-based sports events. The Kirkpinar -- first contested in 1362 -- is considered by some to be the longest continuously running sporting event in the world, lubricated or not.

Kirkpinar is held in late June every year and attracts tens of thousands of spectators to Edirne. A thousand wrestlers take part in an elimination competition over three days, with some bouts lasting for close to an hour. The winner carries the title of best wrestler in Turkey until the next Kirkpinar contest -- and takes home a solid-gold title belt. During the three-day event, wrestlers go through two tons of olive oil.

Aside from copious amounts of olive oil, the sport requires just one piece of equipment: A pair of thick, tight knickers made from water buffalo hide or calf leather. The "kispet" can weigh almost 30 pounds, and is a critical element of the bouts: because their opponents are covered in oil, the leather short pants are sometimes the only thing that provides leverage. The pant legs are sewn shut with thread before the match to prevent opponents from slipping a finger inside for an easy throw.

Perhaps because of its importance in Turkey (and the money to be won) the Kirkpinar is no stranger to the doping controversies that have dogged better-known sports like track and field, baseball and cycling -- organizers began testing oil-slick wrestlers for performance-enhancing drugs back in 1999. And the contest is closed to foreigners, keeping Kirkpinar an all-Turkish affair.

According to legend, the origins of the Kirkpinar competition go back more than 500 years. In 1347, the Ottoman Sultan was traveling through Turkey with 40 of his finest warriors. Two brothers -- Selim and Ali -- started wrestling for fun.

They were so evenly matched that the bout turned into a deadlock, but neither Ali or Selim was willing to call it quits. The pair wrestled long into the night, and eventually died of exhaustion. In the morning, their friends buried them under a fig tree. A year later, the sultan and his men returned to the gravesite and found that 40 springs had appeared. The wrestling contest later became an annual festival.