Promoter Eddie Hearn believes boxing may as well "pack up and go home" if Anthony Joshua's fight against Oleksandr Usyk later this year is not in front of a full house.
Hearn has been to events all over the world which have been staged in front of massive crowds but there are still restrictions in place in this country.
The Usyk fight - a substitute for the all-British heavyweight showdown with Tyson Fury which collapsed after a legal ruling in the United States ordered Fury to face a second rematch against Deontay Wilder - has been pencilled in for September 25 at the Tottenham Stadium.
By then England should be free of Covid-19 restrictions, even if rising rates of the more infectious Delta variant are a cause for concern, and Hearn is hopeful boxing will be back in front of capacity crowds again.
"Full. Full. It is a must. I've just come back from Mexico, in Dallas a few weeks ago there were 73,000," he said.
"It is depressing what we are seeing over here, to be honest with you. But we have to follow the rules.
"If we don't have a full crowd by the end of September we might as well pack up and go home.
"And that includes the Premier League because they, and all football, will be butchered if the Government don't open up grounds for the new season.
"It is very difficult for anyone to make a balanced or correct decision but when you look at the rate of our vaccines you'd have to say you have to 'open up'.
"It is ridiculous now. You've seen cases rise but you see hospital admissions not rising, you see everyone who is vulnerable becoming vaccinated.
"It is very frustrating that we are doing shows all over the world with either full capacity or nearly fully and we can't get the same here. Fingers-crossed by September we'll be good to go."
Hearn, who was announcing the signing of long-time BBC commentator Mike Costello to sports streaming platform DAZN, admits he has to be more careful on social media after letting slip details of the Joshua fight on Friday.
"I was only doing an Instagram Live and someone said to me Joshua and Usyk, and I said 'It looks like September 25 at Spurs'. Bang! In every newspaper," he added.
"We have a call tomorrow to finalise any points in the contract, which are all minimal, and moving the forward that is the likely date. It's not cast-iron but it is the preference.
"Obviously we were due to do the (Kubrat) Pulev fight with Spurs pre-pandemic so we are still looking to do a show at the stadium and hopefully we can move forward to an official announcement at some point."