He grabbed two more golds at the London 2012 Olympics, again setting a new mark in the 1500m — a record that still stands.
But then came the first in a long list of flashpoints. In 2013, Sun fell out with long-time coach Zhu Zhigen after a row over the swimmer’s romantic ties with a flight attendant.
Sun refused to train after Zhu ordered him to end the relationship. Chinese swimming officials attempted to mediate but the damage was done and Sun split with Zhu after 10 years under his tutelage.
Months later, Sun, driving without a license, slammed a borrowed Porsche SUV into a bus in his home city of Hangzhou, near Shanghai. He spent seven days in police detention and later vowed to mend his ways.
At the 2014 Asian Games in Incheon, Sun was at the center of controversy again, describing the national anthem of Japan, China’s arch-rivals, as “ugly” after losing to Kosuke Hagino in the 200m freestyle.
In November 2014 came the bombshell announcement that Sun had served a three-month suspension earlier that year for taking a banned stimulant. He has always maintained it was prescribed medicine for a heart condition.