Anthony Joshua's world heavyweight fight against mandatory challenger Kubrat Pulev will not be postponed again, even if it has to be held behind closed doors, says Eddie Hearn.
The pair will potentially meet on 12 December at London's O2 Arena, having originally been scheduled to fight in June at Tottenham Hotspur Stadium.
Promoter Hearn said sport "can't afford to sit and wait for what might be".
Britain's Joshua, 30, last fought in December when he beat Andy Ruiz Jr.
Culture Secretary Oliver Dowden will meet sports bodies on Wednesday to discuss allowing 1,000 fans into events, which could pave the way for fans to attend boxing matches.
Hearn told BBC Radio 5 Live: "Every sport is in trouble without fans. We have got to do what is right. We have got to listen to the government but we have got to try and make sure we can bring them back.
"Hopefully this is the next phase of doing that and the venues will be dependent on whether fans will be allowed back into the arenas."
Bulgarian Pulev, 39, is mandatory challenger to Joshua's IBF belt, with the Briton also holding the WBA, WBO and IBO world titles.
Hearn added: "Anthony hasn't boxed for a year and the ultimate thing is he needs to progress his career. He wants to learn, he wants to fight, he wants to be active and we live in a world now where you can't wait.
"You've got two options: you either sit and wait - and that includes Anthony Joshua - maybe until next year, or you get out there and you fight, you earn your money, you learn your craft and you continue to battle through it.
"We hope that there is some sunshine over the hill with this whole nightmare.
"We are not prepared to sit tight and wait and we have said in these schedules, fans or no fans, our fights will be taking place.
"If you're a business, if you're a sport, you can't afford to sit and wait for what might be."
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