One of the biggest sponsors of the Olympics, Toyota, has announced it will not run Tokyo 2020-related adverts on TV during the Games because of the lacklustre public support in Japan. Toyota’s chief executive, Akio Toyoda, and other senior executives will also not attend Friday’s opening ceremony in a further blow to these troubled Olympics.

“It is true that Toyota will not be attending the opening ceremony, and the decision was made considering various factors including no spectators,” a Toyota spokesperson said. “We will not be airing any commercials related to the Games in Japan.”

The Games suffered a further blow on Monday when the Czech beach volleyball player Ondrej Perusic was named as the third athlete to test positive in the Olympic village. It means Perusic and his partner David Schweiner will miss their opening match on 26 July and could be ruled out of the entire event.

However the Czech Olympic Committee said it was seeking a postponement of the players’ first game in the hope Perusic, who is fully vaccinated and has no symptoms, can still play. Martin Doktor, the COC chef de mission, said the organisation was looking at “other options that would allow the boys to enter the tournament later, according to the rules”.

Meanwhile organisers face an anxious wait to see if the 60 Japanese corporations who have paid more than $3bn for sponsorship rights follow Toyota in untying their brands from an event that has so far failed to win public support.

“These partners and sponsors must have been struggling to support Tokyo 2020,” said the Tokyo 2020 spokesperson Masa Takaya. “Of course, there is mixed public sentiment towards the Games. There must be a decision by each company in terms of how they should be able to convey their messages to the public from its corporate perspective.”

With only four days before the opening ceremony, 68% of respondents in an Asahi newspaper poll expressed doubt about the ability of Olympic organisers to control coronavirus infections, with 55% saying they were opposed to the Games going ahead.

However the IOC president, Thomas Bach, has repeatedly said there is “zero risk” of participants at the Games spreading the virus to the Japanese public because of the strict measures in place at the event.

Three-quarters of the 1,444 people in the telephone survey said they agreed with a decision to ban spectators from events.