The ATP Tour Finals at the O2 in London is due to be played behind closed doors in November.
The season-ending tournament, which features the best eight singles players and doubles teams of the year, will be played between November 15 and 22.
However, in what is its last outing in London before heading to Turin in 2021, there will be no fans inside the area unless current guidance from the government changes.
An ATP statement read: "In line with existing UK government guidance, the ATP currently plans to hold the 2020 Nitto ATP Finals behind closed doors due to the ongoing Covid-19 pandemic.
"Fans who have already purchased tickets or hospitality to the event through the tournament's official partners will receive full refunds.
"However, ATP remains hopeful that later this year fans will be allowed to return into stadia in a socially distanced manner, following a series of pilot events being undertaken in the UK.
"If this is confirmed ahead of the Nitto ATP Finals, the intention is to reopen ticket sales for the tournament, in which case more details will be announced in due course."
The ATP has also announced a revised calendar for the rest of the season following a five-month suspension due to coronavirus, which sees the Asian-swing scrapped.
The Tour resumes on August 22 with the Western & Southern Open in New York followed by the US Open at the same venue.
A shortened clay-court swing follows, culminating in the French Open on September 27, before a five-week indoor European stint.