In the spotlight:

SUN YANG (CHN)

The bad boy of Chinese swimming, Sun will be looking to add the world title to his Olympic gold medal in the 400m freestyle after a helter-skelter couple of years which also saw him banned for three months for a doping offense.

Stunned by Japan's Kosuke Hagino in the 200m at last year's Asian Games, the Chinese giant courted more controversy by poking fun at the Japanese national anthem before exacting revenge on Hagino over eight laps.