Wang took over the lead from Cai with 3km to race to break for victory, Bird-Smith on his coat-tails.

Wang then powered away to a convincing gold-medal performance in 1min 19.14 sec, Cai clocking 1:19:26 and Bird-Smith a personal best of 1:19:37.

Wang, who won bronze at London Games four years ago, went into the race as the in-form walker having won five of his past six outings over this distance.

He is unbeaten over any distance in 2016 and since he won the Asian Games title in September 2014, the only blip has been his second place in Beijing.

Current world champion Miguel Angel Lopez could only finish 11th, in 1:20.58, as he failed in his bid to win Spain's first athletics gold medal at the Olympics since it staged the Games in 1992.

And Olympic champion Chen Ding of China was down in 39th place in 1:23.54.

South Korea's Kim Hyun-Sub set the early pace on the course alongside the Pontal ocean front southwest of central Rio de Janeiro.

In cooler-than-normal race walking temperatures of around 23 degrees Celsius (73F), they passed 14km in 56:08, the lead changing between Cai and Briton Tom Bosworth, with up to 10 walkers still in touch.

First Cai took up the pace to split the pack before Wang asserted his authority for a commanding victory.

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