For the frenzied partisan crowd at Wimbledon, former champion Andy Murray’s nerve-racking five-set victory against German Oscar Otte on Wednesday evening just about magicked away the pandemic.

“We were feeding off each other a lot at the end,” the Scottish tennis player said. “I hope the fans like it and don’t think that it’s a bit weird that I’m sort of staring at them and screaming at them for like an hour, but they seem to enjoy it as well.”

It’s the sort of interaction that is a reminder of the power that fans have to dictate outcomes in sporting contests. The result might have been different had the event in south London taken place behind closed doors.

Under a UK government programme to assess how safe it is to hold big sports events during the pandemic, fans are allowed to sit next to each other on centre court, albeit to just half its 15,000-capacity.

But the illusion of normality contrasts with the players’ strict “bubble”, the cost of preventing the virus from spreading among the stars of the show and to enable them to avoid quarantine.

All the players and their three-person support teams - a fraction of the usual number - are staying at the same central London hotel and are not allowed to go anywhere other than the tournament grounds to practise or compete. There is regular Covid testing and they have to travel in special vehicles.

As the grand slam tournament approaches the halfway mark, the strength of the bubble matters more because of the risk of losing star players to the virus, an unwanted additional risk to injury or the tactic, primarily employed by older players, of missing certain tournaments to recuperate.

The bubble not only allows the All England Lawn Tennis & Croquet Club, the 153-year-old institution that organises the championships, to hold the tournament but to reduce the number of stars who have had to withdraw.

There have already been casualties, including Johanna Konta, the top-ranked British women’s player, who was forced to self-isolate after one of her team tested positive for Covid.

The restrictions add to the pressure for players who also competed in the French Open at Roland Garros last month, another of the four grand slam majors, as they move from one bubble to the next, with the gap between the two tournaments shorter than usual because of the pandemic.

Stefanos Tsitsipas, runner-up at the French Open and third seed at Wimbledon, said he has been “much more motivated” in the past and partly blamed the bubble for his shock first-round exit.

“The bubble makes it really tiring week by week,” he said. “It’s certainly very difficult when you know mentally you’re going to go from one bubble, being in that bubble two-and-a-half weeks, maybe even more than that, like close to a month.”

Even Nick Kyrgios, Australia’s self-proclaimed “bad boy of tennis”, is changing his prematch routine. His preparations for a clash with Spain’s Rafael Nadal in 2019 included a night out at the Dog & Fox pub in Wimbledon village.

“Yesterday I was here at 12, I warmed up, I was here all day,” he said on Wednesday. “Finished, got back to my hotel at 1. In a bubble. Woke up, got back here. It’s not easy.”

Poland’s Iga Swiatek has been passing the time watching movies and playing with Lego toy bricks. “Even though we’re in a bubble, it doesn’t feel like it because the hotel is really, really big,” she said.

Before being forced to withdraw, Konta said the hotel bubble was “kind of like an all-inclusive cruise”, though she noted that her pet dogs were not allowed in.

The importance of the bubble in keeping players safe has been reinforced by the scant opportunity ahead of the tournament for them to practise, let alone compete, on grass — a slicker and quicker surface than the clay of Paris or the hard courts in Melbourne and New York — the other grand slams. The problem was compounded by the fact Wimbledon was cancelled last year for the first time since the second world war.

The result is a conspicuously high number of players either suffering injuries or skipping the tournament, adding to the organisers’ headaches as they seek to ensure as many stars as possible make it through to the final rounds.

To make matters worse, in recent days there have been multiple complaints about the slippery state of the show courts.

Serena Williams, the American chasing a record-equalling 24th grand slam title, retired after slipping and injuring her ankle in the first round. Her exit came almost immediately after Roger Federer, the Swiss star with more Wimbledon singles titles than any other man, progressed from the first round because his opponent fell.

Among those who had did not even make it to the first round were Nadal, another former Wimbledon winner who decided not to participate in order to prolong his career, and Simona Halep, the women’s defending champion who suffered a calf injury. Meanwhile Naomi Osaka, the world number two, is taking a break after revealing a battle with depression.

Novak Djokovic, the men’s favourite and defending champion, said he could not remember slipping as much as he did in his first-round victory. Murray described the centre court surface as “extremely slippy” after Williams injured herself.

The AELTC defended the surface after the injuries and criticism from players. Rainy conditions on the opening two days did not help.

“The preparation of the grass courts has been to exactly the same meticulous standard as in previous years,” said the AELTC. “With each match that is played, the courts will continue to firm up.”