World Health Organization director-general Tedros Adhanom Ghebreyesus said Wednesday the Tokyo Olympics should go ahead to show to the world what can be attained with the right set of plans and measures in the face of a Covid-19 pandemic.

Competition started Wednesday morning with Japan's softball team playing against Australia at the Fukushima Azuma Baseball Stadium. Olympic events typically kick off before the formal start for scheduling purposes.

The Tokyo Olympics opening ceremony will be held Friday, after a one-year delay, weeks of negative headlines and public backlash.

But as the virus continues to cause a disturbance throughout Japan, anything can still happen.

It is still not clear whether the public health measures in place are enough to prevent the Games from becoming a major superspreader event.

Athletes have already started arriving and more than 70 infections linked to the Olympics have been detected, CNN said.

On Tuesday, an American gymnast and a Czech beach volleyball player tested positive for the virus, The Associated Press said.

Still, the International Olympic Committee and Japanese authorities said the Games will go on for now. The budget has already grown to an estimated $15.4 billion, Reuters reported.

Opinion surveys in Japan show most people are not in favor of hosting an international sporting event during a pandemic.

Ghebreyesus, who is in Tokyo for the Games, expressed confidence Japan could safely host the Olympics.

"There's no zero risk in life; there's only more risk, or less risk. And you have done your best," the World Health Organization chief said.

Rising infections in Tokyo have cast a shadow over a sporting spectacle that, having already been postponed last year because of Covid-19, will now take place without spectators.

Toshiro Muto, Japan's chief Olympics official, did not rule out canceling the Olympics last minute Tuesday.