Professor Dame Angela McLean, deputy chief scientific adviser to the Government, says it is an "interesting hypothesis" that Liverpool's Champions League match against Atletico Madrid may have spread coronavirus in the city.

More than 3,000 fans made the trip from the Spanish capital to Merseyside for the March 11 fixture, despite their home city already subject to partial lockdown amid the Covid-19 pandemic.

McLean admits it will be interesting to look at the scientific evidence and the Champions League last-16 second leg tie at Anfield down the line, but pointed out that, given the general policy at the time, going to a football match was not considered a "particularly large extra risk".

"However, when you get to the situation of our strange lives as we live them now where we spend all our time basically at home, of course you wouldn't add on an extra risk of lots and lots of people going off to the same place at the same time," she continued.

World number one Novak Djokovic's opposition to vaccines could stand in the way of his return to tennis once it resumes from the coronavirus pandemic.

A push is growing for all players to be vaccinated when tennis starts again, provided a vaccination is produced by then.

"Personally I am opposed to vaccination and I wouldn't want to be forced by someone to take a vaccine in order to be able to travel," Djokovic said in a live Facebook chat with several fellow Serbian athletes on Sunday.

"But if it becomes compulsory, what will happen? I will have to make a decision."