Chinese swimming star Sun Yang is preparing for the upcoming FINA World Championships 2013 in Barcelona by himself, leaving his future murky following a public row with his coach, Zhu Zhigen.

The Olympic gold winner was missing from China's swimming team, which arrived in Beijing for intense training. The team was led by Coach Zhu, whose fallout with Sun Yang was in the spotlight.

Sun has been training on his own at Zhejiang Vocational College of Sports, said Zhang Yadong, the school's vice president. It's uncertain when Sun Yang will join his teammates, Zhang added.

Sun Yang has asked for a new coach. He has been training by himself until a new coach can be appointed.

The duo made a public gesture by hugging in the limelight on March 4, indicating that the conflict was over. However, that seems far from the end of the story.

Sun shot to fame after winning the 400m, 1,500m freestyle and 4x100m freestyle relay at the London Olympics. His spat with his coach, who has been with him for 10 years and led him to Olympic glory, surfaced after the two failed to reach agreement on Sun's commercial activities schedule and relationship with his girlfriend.

The drama caused a stir among sports fans, who have already started to worry about Sun Yang's performance at the Barcelona tournament, which is slated to be held in July.