Softball match takes place two days before the official opening ceremony of the COVID-hit 2020 Games.

Japanese pitcher Yukiko Ueno delivered the first ball of the pandemic-hit 2020 Tokyo Olympics on Wednesday morning amid continuing doubts about the wisdom of holding the event at a time when the fast-spreading Delta variant is driving a resurgence of COVID-19 in Japan and around the world.

Japan are taking on Australia in softball, with two more softball games, as well as women's football matches scheduled for Wednesday.

Olympics and Japanese officials have pushed ahead with the Olympics despite persistent opposition in the country to hosting more than 11,000 athletes, staff and media that come with them, given the rising number of COVID-19 cases. Tokyo is currently in a coronavirus state of emergency.

Coaches for the six countries competing in the softball tournament applauded organisers on Tuesday for creating a safe environment and said their players particularly appreciated the Olympics not being cancelled.

Japan's starter Yukiko Ueno pitches in the first inning during the Tokyo 2020 Olympic Games softball opening-round game between Australia and Japan at Fukushima Azuma Baseball Stadium in Fukushima, Japan, on July 21, 2021 [Kazuhiro Fujihara/AFP]

Softball was revived for the Tokyo Games after being dropped after 2008. The initial two days of games are being held at a baseball stadium in Fukushima, a region badly affected by the 2011 tsunami and nuclear disaster.

The Tokyo Games were postponed last year shortly after the World Health Organization (WHO) declared a pandemic over the spread of the coronavirus. More than 4.1 million people have died from the disease since, and while vaccinations have helped some countries deal with the health crisis, vaccine inequity and the rise in new variants are creating new problems for a world desperate to return to some kind of normalcy.

Organisers have promised a "safe and secure" Olympics, but many Japanese are sceptical.

The country's vaccination programme has lagged behind that of many other developed nations, and Tokyo is seeing a new surge in cases with 1,387 people diagnosed on Tuesday. In total, Japan has recorded more than 840,000 cases and 15,055 deaths.

Dozens of cases linked to the Olympics, including some athletes, have further undermined public trust in coronavirus mitigation efforts.

On Tuesday, the chief of the Tokyo 2020 organising committee said cancellation could not be ruled out if COVID-19 cases spiked.

Toshiro Muto told a news conference that he would keep an eye on infection numbers and liaise with other organisers if necessary.

"We will continue discussions if there is a spike in cases," Muto said.

"We have agreed that based on the coronavirus situation, we will convene five-party talks again. At this point, the coronavirus cases may rise or fall, so we will think about what we should do when the situation arises."

A spokesman for Tokyo 2020 later said organisers were "concentrating 100 percent on delivering successful Games".

Coronavirus rules mean teams are competing without any fans to cheer them on [Yukihito Taguchi-USA TODAY Network via Reuters]