The Premier League will hold an emergency meeting on Friday, with the Arsenal and Chelsea first-team squads in self-isolation after positive coronavirus tests for Gunners manager Mikel Arteta and Chelsea winger Callum Hudson-Odoi.
This weekend's programme is now in jeopardy after Arsenal confirmed Arteta had contracted Covid-19 before Chelsea reported Hudson-Odoi's case hours later.
The Gunners' trip to Brighton on Saturday was immediately postponed and further games appear certain to follow, while in golf, the US PGA on Thursday called off the Players Championship at Sawgrass after the first round, as well as its scheduled tournaments for the next three weeks.
This morning, Everton announced that one of the squad is now self-isolating after one of their players reported symptoms of coronavirus.
The Premier League could follow the NBA in suspending its season, with US basketball officials clarifying on Thursday the league will be halted for at least 30 days.
Leicester (three) and Manchester City (one) also have players in self-isolation and the Premier League, who earlier on Thursday said games would go ahead as planned, said it would "convene an emergency club meeting regarding fixtures".
Hudson-Odoi displayed cold symptoms on Monday morning and has stayed away from the club since then. His test result was returned on Thursday night.
The club said: "Chelsea personnel who had recent close contact with the player in the men's team building will now self-isolate in line with Government health guidelines. These will include initially the full men's team squad, coaching staff and a number of backroom staff."
The club said despite testing positive, the 19-year-old was "doing well and looking forward to returning to the training ground as soon as it is possible".
The news on Hudson-Odoi's positive test follows confirmation that Arsenal boss Arteta has also been infected with the virus.
As a result, the north London club's training centre has been closed in an attempt to contain further outbreaks of the coronavirus.
As things stand, Premier League matches are still scheduled to go ahead this weekend, as the British government haven't advised its sporting bodies to postpone sporting events.
However, in light of Arteta's positive test, this situation could change in the coming days, with the Premier League holding an emergency meeting of all clubs on Friday.
Arteta said in a statement: "This is really disappointing but I took the test after feeling poorly. I will be at work as soon as I'm allowed."
A number of high-profile sporting events around the world have already been cancelled due to the coronavirus pandemic with Sunday's Australian Grand Prix becoming a casualty on Thursday night.
The race, which was due to take place in Melbourne on Sunday, was called off after a member of the McLaren team tested positive.
McLaren had already decided to withdraw but, following a meeting of race organisers and team bosses, the race was cancelled.
A statement from the sport's governing body, the FIA, read: "Those discussions concluded with a majority view of the teams that the race should not go ahead. The FIA and Formula 1, with the full support of the Australian Grand Prix Corporation have therefore taken the decision that all Formula 1 activity for the Australian Grand Prix is cancelled."
A number of other high-profile sporting events around the world have also fallen victim.
However, widespread cancellations are not yet occurring in the UK.
On Thursday prime minister Boris Johnson said the country was now moving into the next stage of its planning to combat the pandemic - the delay phase. However, he said that does not yet include cancelling sports events.
"We are considering banning major public events like sporting fixtures," he said.
"The scientific advice is this has little effect on the spread - but it does place a burden on other public services."
Elsewhere it has been a different story with some Champions League games, ATP tennis events and most major American sport stopped.
UEFA will also give major consideration to delaying this summer's Euro 2020 tournament until next year. European football's governing body has called a meeting of its 55 member associations next week to discuss the matter.
Already next week's Manchester City v Real Madrid and Juventus v Lyon Champions League matches have been postponed. The entire Real squad is in self-isolation, while a Juventus player has tested positive.
The Football Association of Ireland has announced all football activity under its jurisdiction has been suspended until March 29 and Wales' friendly against the United States on March 30 is off.
All Irish horse racing will take place behind closed doors until March 29 and, in Scotland, First Minister Nicola Sturgeon has said she would recommend the cancellation of gatherings of more than 500 people.
In rugby union, the Guinness PRO14, which features Scottish, Welsh, Irish, Italian and South African clubs, has also been suspended.
In tennis the ATP Tour has announced a six-week suspension of activity. Aside from the men's Players Championship abandonment the ANA Inspiration - the first women's major of the year - is among five LPGA tournaments cancelled.
Major League Soccer, Major League Baseball, the NBA and NHL have all been paused in the United States. Other FIBA, NCAA and EuroLeague basketball games are also affected.
Other positive tests for coronavirus include former Southampton forward Manolo Gabbiadini and Colombian cyclist Fernando Gaviria.
A club statement read: "Our London Colney training centre has been closed after head coach Mikel Arteta received a positive COVID-19 result this evening.
"Arsenal personnel who had recent close contact with Mikel will now self-isolate in line with Government health guidelines.
"We expect this to be a significant number of people from Colney, including the full first-team squad and coaching staff, as well as a smaller number of people from our Hale End Academy which we have also temporarily closed as a precaution.
"We expect those who did not have close contact with Mikel to return to work in the coming days. In the meantime our Colney and Hale End training centres will undergo a deep clean and our other club sites are operating as normal."
Managing director Vinai Venkatesham said: "The health of our people and the wider public is our priority and that is where our focus is.
"Our thoughts are with Mikel who is disappointed but in good spirits. We are in active dialogue with all the relevant people to manage this situation appropriately, and we look forward to getting back to training and playing as soon as medical advice allows."
Head of football Raul Sanllehi added: "Mikel and the full first-team squad, players and staff, will be fully supported, and we look forward to getting back to training and playing as soon as medical advice allows. Obviously Mikel’s full recovery is the priority now for us all.
"We will work with Public Health England on the next steps in regard to our facilities and staff, and with the Premier League, Football Association and relevant clubs around our forthcoming matches in the Premier League and Emirates FA Cup.
"It is clear we will not be able to play some fixtures on their currently scheduled dates. We will update supporters who have tickets for forthcoming games with more information as soon as possible.
"We are now working to trace any other people who have had recent close contact with Mikel. We will let them know what has happened and they should follow the NHS guidance which is likely to recommend self-isolation."
Arsenal have confirmed that their Premier League match against Brighton this weekend has been postponed.