Mercedes say Lewis Hamilton's health is "improving" - but still do not know whether he will be able to race in the year's final grand prix this weekend.
The world champion missed the Sakhir Grand Prix in Bahrain last weekend after
contracting coronavirus.
Hamilton remains in isolation and must return a negative test result before he is allowed to travel to Abu Dhabi.
"His condition's improving but we won't know closer to the time if he will be driving," said team boss Toto Wolff.
"We'll do everything we can to get him in the car and we know he's determined to be back as soon as possible. But his health is our main priority, so we will see what the situation is and then make the call."
Russell has been named as Mercedes' representative alongside Valtteri Bottas in the official FIA news conference on Thursday.
The latest Mercedes could put Hamilton in the car and still race is on Saturday for qualifying.
The team said it was "possible" they would make the decision as to whether Hamilton races as late as before Saturday's final practice session, which runs for an hour and starts at 10:00 GMT, three hours before qualifying.