The first gold medal is expected to be awarded on Sunday morning, likely in the men's individual triathlon, with another 468 medals up for grabs across more than 40 sports before the Games conclude on October 4.

The event in Nagoya and Aichi prefecture has 2028 Olympics places up for grabs in seven sports and will be graced by global stars.

But it has been dogged by a series of problems in the lead-up.

The 17,000 participants -- more than the Olympics -- stretched organisers to the limit as they scrambled to find accommodation for everyone.

To save money there is no traditional athletes' village, competitors instead staying in a combination of temporary container-style huts, hotels and cruise ship the Costa Serena.

To add to the issues, there was a record deluge last week which flooded parts of Nagoya city and now a tropical storm is approaching eastern Japan that could cause further disruption on Sunday-Monday.

Some athletes were left stranded at the airport when transport failed to turn up and several teams have complained about the quality of the huts, including the beds being too short.