BEIJING, June 30 -- Olympic and world 200 meters freestyle champion Yannick Agnel announced Monday to end his season after suffering from pleurisy, dropping off the chance to defend his title in the world championships in early August.

It means Olympic and world champions Sun Yang from China may dominate pools of Kazan, Russia this summer. Sun had won gold metals in 400m and 1,500m freestyles in 2012 London Olympic games, but Agnel defeated him in 200m race.

What's more, Sun's good friend and old rival Park Tae-hwan is still in a 18-month-ban after a doping storm. In London's 200m freestyle, Park snatched a silver medal after finishing the tough game with Sun at the same time.

Sun Yang was No. 2 on the 2015 season rankings with his 1:45.75 from Chinese Championships in April, just now was 0.15sec away from the man at the helm, Germany's 2009 world champion Paul Biedermann.

Sun will defend three titles in Kazan, including 400m, 800m and 1,500m freestyle champions. The 23-year-old never slipped out of top eight best records of this three events in 2015 season.

A growing list of stars who will bypass the world championships, including 100m freestyle world champion James Magnussen, Australia teammate Brittany Elmslie, American Michael Phelps, Park from South Korea, Agnel and so on.

Whether how many events Sun will take a part in Kazan, he would be a shining stars all over world, and his gold medals road to Rio 2016 will be constructed from the city.