Russian tennis star Andrey Rublev became the latest player to have played in an Abu Dhabi exhibition tournament earlier this month to test positive for Covid-19 just weeks away from the Australian Open.
The 24-year-old world number five tweeted he was self-isolating which places in doubt his competing in the ATP Cup (Jan 1-9) in Australia.
The Australian Open -- where Rublev reached the quarter-finals this year -- runs from January 17 to 30 in Melbourne.
"I am currently in Barcelona and unfortunately I have tested positive for Covid-19," said Rublev on Twitter.
"I have minimal symptoms.
"I am isolating and respecting all the protocols under the supervision of the doctors.
"As you know I am completely vaccinated and I was preparing for the ATP Cup and Australian Open.
"Now I have to recover and I will go to Melbourne only when I am certain it is safe for everyone.
"I am very upset and concerned about what is happening.
"Please, take care of yourself and of the people around you.
"I will return to the court as soon as possible."
Rublev is the third male player to have played in Abu Dhabi to test positive for Covid.
Canada's Wimbledon semi-finalist Denis Shapovalov tested positive on arrival in Australia and former world number one Rafael Nadal did as well on returning to Spain.
Nadal's coach Carlos Moya also tested positive.
Three female players who were in Abu Dhabi tested positive -- Olympic gold medalist Belinda Bencic, US Open champion Emma Raducanu and Wimbledon quarter-finalist Ons Jabeur.