ON A VAST, GRASSY plot of land 150 miles northwest of Istanbul, the scene will play out the first week in July, much as it has for the past 646 years. Nearly 2,000 men and boys will trek from all over Turkey to the Field of Heroes, near Edirne, to slather themselves with olive oil and face off at Kirkpinar (translation: 40 Springs), the national oil-wrestling tournament. Started by soldiers during the time of the Ottoman Empire and named, according to legend, for mysterious springs that arose at Edirne after two warriors fought there to the death, the three-day, greased-up extravaganza is the oldest ongoing sporting event in the world.

It's also one of the most grueling. Since its inception, in 1362, the rules have been simple: no water breaks, no timeouts. Officials imposed a 40-minute time limit on matches in 1975, but wrestlers in 13 divisions still risk scars and broken teeth in temperatures nearing 100* for the chance to snag medals and money. The winner of the top class also earns the prestigious golden belt as the bas pehlivan-head wrestler. But for many Turks, competing at Kirkpinar means more than the chance to win cash and acclaim. "This is our ancestral sport," says 22-year-old Mustafa Yenisancak, who's wrestled at Kirkpinar since he was 8. "It's our cultural duty."

(1) During each match, grapplers can perform as many as 42 different moves, many of which date back to ancient Greece. But unlike their Hellenic counterparts, the Turks keep their clothes on; in deference to Islamic laws governing modesty, they wear calf-length leather pants called a kispet. (2) Since all of a wrestler's exposed skin is covered with olive oil, there's only one sure way to grasp an opponent: by reaching for the dry flesh under the kispet. In one maneuver, called paca kazik, or pants grab, a competitor grabs his rival in order to lift him into the air. (3) A wrestler wins by performing one of two maneuvers: pinning an opponent on the ground, or taking three steps while carrying him. That's easier said than done, because a scooped-up fighter will try to plant his feet on his opponent's body, then run up his chest and kick off from his shoulders. If neither wrestler performs a match-ending move, judges can award a golden point and declare a victor by decision. (4) Despite fortifying themselves with a protein-rich diet of milk and grilled meats, Kirkpinar's warriors are exhausted at the end of a match. In 2007, 30-year-old heavyweight Recep Kara had to be carried away by friends after a 60-minute victory. (Judges allow close matches to go into overtime.) His respite didn't last long. After being force-fed bananas and ice chips, he returned to the grass 45 minutes later for his next match.

(5) Fighters stride across the field slapping their thighs in a pre-match ritual that is both symbolic and practical: It pays homage to past wrestlers and loosens up the leather pants. Next, they take a knee and run their hands through the grass to mentally prepare for the fight. (6) Competitors apply olive oil, culled from local crops, before every match, making it more difficult for opponents to grab and vanquish them by brute strength alone. Wrestlers fight in several matches over the course of three consecutive days, during which at least two tons of the lubricant are used. (7) A wrestler binds the bottom of his pant legs with rope to keep out grass and an opponent's hands. Competitors who cannot afford $500 for the traditional kispet may wear pants made of heavy green cloth or denim. (8) Wrestlers often twist each other into pretzels for 30 minutes or more before attempting a match-ending move. (9) The only source of relief from the sweltering heat at Kirkpinar is water-between matches-from the seven green metal containers placed in one corner of the field.

(10) All over Turkey, young boys wrestle with friends in hopes of someday participating at Kirkpinar. Villagers often pool resources to send one of their own to the tourney. (11) Children compete in divisions with names like Tiny Adorables and Dustkickers. (12) Turkey's deputy prime minister Mehmet Ali Sahin (front row, in jacket) lends an official government presence to the 2007 festivities, but he's not the big dog here. That distinction belongs to the aga, or patron, who bankrolls the tourney, often to the tune of $200,000-plus. (13) Defeating three days' worth of foes to win a division is a tough task. "It is very painful," says Osman Aynur, 26, a former head wrestler. "But I do it for ego." After Aynur fell in the semifinals in 2007, he ran to a nearby grove of poplar trees, hid his face under a towel and wept. (14) "There are two types of winner," says Nevzat Celik, a local who has dispensed olive oil at Kirkpinar for 11 years. "One who works very hard and is very clever. And one who is just strong." Recep Kara had enough brains and brawn to capture his second bos pehlivan in 2007.