The men's Davis Cup and women's Fed Cup finals have both been rescheduled for next year due to complications posed by the coronavirus pandemic, the ITF announced on Friday.
This year's Davis Cup finals in Madrid, the second instalment of a new-look competition, were due to run 23-29 November while the revamped Fed Cup had been postponed indefinitely after April's finals were called off.
"It's a huge disappointment for all of us that the Davis Cup Finals will not be held in 2020," said Barcelona football star Gerard Pique, whose Kosmos investment group finances the competition.
"We don't know how the situation will develop in each qualified nation, or if restrictions in Spain will remain sufficiently eased, as such it is impossible to predict the situation in November and guarantee the safety of those travelling to Madrid."
The rearranged finals will comprise the 18 teams which qualified for the this year's edition. It will instead begin the week starting 22 November, 2021.
"This is a tough decision to have to make, but delivering an international team event on this scale while guaranteeing the health and safety of all involved ultimately poses too great a risk," said ITF president David Haggerty.
Spain has one of the worst affected countries by the pandemic, suffering more than 28 000 deaths, but started reopening its borders at the end of last week.
The announcement capped a bad week for tennis after world number one Novak Djokovic's exhibition tournament in the Balkans led to him and other top players Grigor Dimitrov, Borna Coric and Viktor Troicki testing positive for Covid-19.
All professional tennis has been in cold storage since mid-March with Wimbledon cancelled for the first time since the World War II and Roland Garros moved back to September and October.
The US Open is going ahead as scheduled in New York from 31 August, although the rash of positive tests at Djokovic's event has raised questions about the resumption of the season.
A number of Davis Cup qualifiers in March were played behind closed doors at the onset of the global health crisis. World Group I and II ties scheduled for September will be pushed back until next year.
The revised 12-team Fed Cup finals were initially due to take place on indoor clay in Budapest from 14-19 April but were shelved in response to the virus outbreak. They have been reprogrammed for 13-18 April, 2021.
"Due to the ongoing challenges presented by the Covid-19 pandemic, it has not been possible to reschedule the postponed Finals in 2020," the ITF said on Friday.
"In addition to the Laszlo Papp Arena being unavailable over the latter part of the year, there remain significant logistical and regulatory challenges that mean hosting an indoor mass gathering while guaranteeing the health and safety of all involved will not be feasible."
Eight Fed Cup play-off ties to be held at various venues around the world were also put on hold in March. They will be played next February.
"While it is regrettable that the Finals will not be able to take place this year, we are confident that we will be able to host a superb event in Budapest in April 2021," said Haggerty.
"In these extraordinary times, we believe that the best way forward in order both to protect the health and safety of all involved and to best respect the integrity of the competition is to extend this year's Fed Cup into 2021, with the event returning to an annual basis the following year."
The move to reform the Fed Cup followed a similar overhaul of the Davis Cup, with Madrid hosting the inaugural finals won by Rafael Nadal's Spain in Madrid last November.
The previous format, which saw the eight-team World Group decided over three ties separated over the course of the season, was criticised for being too protracted and for not protecting player welfare which led many top players to stop representing their countries.
The new-look tournament will offer a total prize pot of $18 million with $12 million going to players and $6 million to national tennis associations.
The finals will feature four groups of three teams, with the winners progressing to the semi-finals and final. All matches will consist of two singles and one doubles.
France won last year's competition after beating Australia 3-2 in the final in Perth.