Formula One champion Lewis Hamilton has said he is "gutted" he won't be able to race in this weekend's Sakhir Grand Prix in Bahrain after testing positive for coronavirus.
The British driver's Mercedes team said he had three negative test results last week but woke up on Monday morning with "mild symptoms".
A statement said that Hamilton, 35, was informed at the same time that someone he had been in contact with before his arrival in Bahrain had tested positive.
In a post on Twitter, Hamilton wrote: "Hi guys, I'm devastated that I won't be racing this weekend. Since we started the season in June my team and I have been taking all the precautions we possibly can and following the regulations everywhere we have been in order to stay safe.
"Unfortunately, even though I returned three negative results this past week, I woke up yesterday morning with mild symptoms and requested another test which came back positive. I have immediately gone into self-isolation for 10 days.
"I am gutted not to be able to race this weekend but my priority is to follow the protocols and advice to protect others.
"I am really lucky that I feel OK with only mild symptoms and will do my best to stay fit and healthy.
"Please look after yourselves out there, you can never be too careful. These are worrying times for everyone and we need to make sure we are looking after ourselves and each other. Stay positive."
Mercedes will announce Hamilton's replacement later - their reserve drivers are Stoffel Vandoorne and Esteban Gutierrez.
Hamilton, who wrapped up his record-equalling seventh world championship in Turkey last month, is the third driver to have contracted the illness.
Sergio Perez missed the British and 70th Anniversary Grands Prix at Silverstone in August, while his Racing Point team-mate Lance Stroll also tested positive following October's Eifel Grand Prix in Germany.
Hamilton appeared to be drained after winning the first Grand Prix in Bahrain on Sunday.
"It's physical, this track has always been physical. We've got lots of high-speed corners so I was definitely feeling it," he said soon after the race.
"I was sliding around a lot out there and I wasn't really quite sure how it would play out at the end."
There is another race in Bahrain on Sunday - on Sakhir's shorter outer circuit - before the 17-race season concludes in Abu Dhabi.
Russell to stand in for F1 champion Hamilton at Sakhir