Zou also won two Olympic gold medals (2008, 2012) and a bronze (2004), but now faces his toughest challenge in his seventh professional fight at Cotai Arena against a foe he knows all too well from his amateur days.
Zou first encountered International Boxing Federation champion Amnat in 2007 when the Thai, in his first event since being released from prison, pulled off a huge shock to beat Zou, who had already won his first amateur world championship two years earlier.
Zou and Amnat were to meet twice more and the Chinese boxer won both fights on close points decisions, with the last encounter coming almost five years ago in the Asian Games.
The pair have become good friends, but Zou said that would have to be cast aside once the bell rings for the first of 12 rounds on Saturday night.
“We are professionals and although it’s true we are good friends, when he is in the ring I will want to hurt him, to try to kill him,” said Zou, who under Hall of Fame trainer Freddie Roach has a perfect professional record of six wins from six.
Amnat turned pro earlier than Zou, after failing to be selected for the 2012 Olympic team, and boasts a perfect 14-fight record with five knockouts.
He will be making the third defence of the title he won against Rocky Fuentes of the Philippines just over a year ago.
Zou was groomed for success by China’s elite sporting programme ever since excelling as a schoolboy boxer, but Amnat took a very different path to the top.
Former drug addict Amnat, 35, had been sentenced to his third jail term for drugs and robbery offences back in 2006 when the street kid found salvation by signing up for the notoriously tough Thai correctional system’s boxing programme.
Within a year he had won the Thai national championship, despite still serving a heavy 15-year term handed down under the “three strikes and out” policy for snatching a woman’s handbag.
His dedication to boxing training and success with the gloves meant that he was released the very next day for “good behaviour” after serving just a year of his sentence.
He never looked back — “boxing lifted me”, he says — and in his next event beat Zou in the prestigious King’s Cup.
Amnat is confident of retaining the title, despite all the hype and support the hugely popular Zou is enjoying in southern Chinese city Macau.
“Zou says he will take the belt to China, but I can tell you it will stay in Thailand,” Amnat said this week.
China has only once before had a world champion outside of the amateur ring, and that was at the little recognised WBC “minimum weight” (light flyweight) category which Xiong Zhaozhong won in 2012 and defended twice.
Such is Zou’s celebrity status in China — he even had a cameo role in the blockbuster Transformers 4 movie — that veteran fight promoter Bob Arum claimed this week that a potential TV audience of 300 million will watch the fight, which will be shown live on the national CCTV5 network.