Italian Massimo Stano has upstaged the Japanese favourites to win gold in the men's 20km walk at the Tokyo Olympics.

Stano surged clear in the final kilometre to clock a winning time of one hour 21 minutes, five seconds ahead of Japanese duo Koki Ikeda and reigning world champion Toshikazu Yamanishi.

It was the third athletics gold for the Italian team at the Tokyo Games, following Lamont Marcell Jacobs' shock win in the men's 100m and Gianmarco Tamberi's shared high jump gold.

All three of the Olympic walks and the two marathons are being held in the northern Japanese city of Sapporo to avoid the intense heat and humidity of Tokyo, although the temperature still reached 30 degrees Celsius during Thursday's race.

Australia's best 20km walk medal hope, 2016 Rio Games bronze medallist Dane Bird-Smith, withdrew on the eve of the Games citing family medical reasons.

In his absence, Declan Tingay was the first Australian across the line in a personal best time of 1:24.00, finishing 17th overall.

Kyle Swan was 36th in 1:27:55.