Ronnie O'Sullivan says having a crowd at the World Snooker Championship is an "unnecessary risk".
World Snooker says the Sheffield event will host a "reduced crowd" after discussions with government.
Spectators will be asked to "follow a code of conduct" at the event, which begins in Sheffield on 31 July.
But speaking to BBC Radio 5 Live about the idea of having a smaller crowd, O'Sullivan said: "You aren't really achieving anything."
The five-time world champion added: "Having people there but not enough people doesn't look good. Either pack it out and say we don't actually care or just go 'we aren't having anyone'."
The tournament has been chosen as one of a handful of events to stress-test the UK government's guidance on fans returning to elite sporting events after the coronavirus shutdown.
World Snooker Tour chairman Barry Hearn said players who have commented that the tournament will not be the same without fans "will be thrilled".
Fans have already been asked if they would like the chance to keep their ticket and those who responded stating they would will now be given a place among the crowd at the Crucible Theatre.
O'Sullivan says he has "no problem" with sporting events being behind closed doors until 2021, given the risk of coronavirus infection.
"Just sport being on television is enough at the moment," said the 44-year-old.
"I just think it's an unnecessary risk. I just don't think you want to be putting people's lives at risk. You look at the NHS and you think this is like a war at the moment and it's those people who have been flat out, and you watch what they go through, and anything to take the stress off them is paramount."
He says playing is a "risk I'm prepared to take" but that he will assess how he feels at the venue and that if he is "very, very uncomfortable" he would withdraw.
"If I get to that point then obviously there is no point in playing," he said. "And hopefully I don't, hopefully I feel like I'm there and I'm enjoying."
The 2020 World Championship will be live on BBC TV, BBC iPlayer, BBC Red Button, the BBC Sport website and the BBC Sport app.
- 'I'll swallow blood before my pride': Meet Scotland's first pro female boxer
- Lockdown love life: How can romance spark in a global pandemic?