Liu Xiang plays with toy hurdles during a charity event at Shanghai Pudong Special School in this May 2011 file picture. The former Olympic gold medalist will be looking to win his fourth Asian title at the Asian athletics championships in Kobe this weekend.

Former Olympic gold medalist Liu Xiang of China will be aiming for his fourth continental title at the Asian athletics championships in Japan, as the region's top athletes build up toward August's world championships.

With August's worlds in South Korea looming, along with next year's Olympic Games, there should be plenty to motivate the 500 athletes from 45 countries taking part in the July 7-10 meet at Kobe Universiade Stadium.

Liu, the 2004 Athens 110-meter hurdles gold medalist, shortened his spring season to avoid stress on a tender heel but will be among 21 champions from last November's Asian Games taking part in the event. He has looked strong this year. He was second to American David Oliver at the Prefontaine Classic last month with a time of 13.00; his best time since winning the world championships in Osaka in 2007.

China won 13 gold medals as host of last year's Asian Games in Guangzhou and is sending a contingent of 41 athletes, including Li Yanxi, who holds the Asian record in men's triple jump.

But the championships will open under a cloud of controversy after eight Indian athletes tested positive for banned substances in the space of five days. Asian Games double-gold medalist Ashwini Akkunji and sprinter Priyanka Panwar were among those who tested positive during a camp in the northern Indian city of Patiala on June 27. Akkunji and Panwar were to be part of the 37-member Indian squad for the games.

Nigerian-born Femi Ogunode of Qatar will highlight the men's sprint events. Ogunode won gold in both the 200 and 400 meters at the Asian Games but will be competing in just the 200 here.

Kenyan-born Ali Hasan Mahoob, the Asian Games 5,000 meters gold medalist, has moved up to the 10,000 where he will face Ethiopian-born Bahrain teammate Bilisuma Gelasa, who is the Asian Games gold medalist in the event.

Kazakhstan's Dmitriy Komkov, who won decathlon gold in Guangzhou, is entered in the 400 hurdles where he will face Joseph Ganapathiplackal of India, who won the 400 hurdles gold at the Asian Games.

The absence of Japan's Koji Murofushi means Tajikistan's Dilshod Nazarov and Kuwaiti Ali Mohammed Al-Zankwai should fight out the hammerthrow title. Nazarov is the defending champion and the Asian Games champion. Olga Bludova of Kazakhstan will be the one to watch in the women's 100.