With the Beijing Games looming, potential Olympic champions will be looking not only for medals but for top-class performances when they converge on Valencia for the World Indoor Championships this weekend. The evergreen Maria Mutola, long distance sensation Meseret Defar, pole vault queen Yelena Isinbayeva and 60 meters hurdler Susanna Kallur will be among the attractions in the women's events. As for the men, there are mouth-watering contests in prospect in the 60 meters hurdles, the shot put and the middle distance events, while Olympic champion Stefan Holm will be targeting a fourth indoor crown in the high jump. Although he cannot compete in Beijing, British sprinter Dwain Chambers will also be in the spotlight after his controversial return to athletics following a two-year doping ban for the designer steroid THG. The man who used to run the World Anti-Doping Agency (WADA) believes the rule that prevents Chambers from competing at the Olympics because of his drug-taking past may not be enforceable in law. “As a matter of law, I think the BOA would be on pretty shaky ground,” the 65-year-old told BBC Sport. For Mutola Valencia will be a special occasion as she bids for an eighth gold medal in the 800 before she retires at the end of the season after 15 years at the top. Mutola, who won Mozambique's first Olympic gold in Sydney in 2000, will face tough competition with Russia's Natalya Ignatova and home favourite Mayte Martinez amongst her rivals. Ethiopia's Defar is one of four world outdoor and indoor champions competing in Valencia. The world and Olympic 5,000 meters gold medalist is hot favorite to emulate Gabriela Szabo and win a third consecutive 3,000 meters title, while world record holder Yelena Soboleva will take some beating in the 1,500. Pole vaulter Isinbayeva broke the 21st world record of her career when she set a new indoor best of 4.95 meters in Donetsk last month. But the 25-year-old suffered her first defeat since Feb. 2004 when she lost to fellow Russian Svetlana Feofanova in Bydgoszcz last month. Swedish hurdler Kallur set a new world's best of 7.68 in the 60 meters hurdles in Karlsruhe last month, proving she is on course for a successful defense of her Olympic title in Beijing. A notable absentee, however, will be compatriot Caroline Kluft who had to withdraw from the heptathlon because of injury, leaving the way open for rival Kelly Sotherton to take the multi
