Mercedes F1 boss Toto Wolff says the team's situation is still fluid regarding who will partner Valtteri Bottas this week at the Abu Dhabi Grand Prix.
Lewis Hamilton remains in isolation in Bahrain and while his condition is improving, he will need to deliver several successive negative COVID-19 tests and permission from Abu Dhabi's authorities to enter F1's biosphere at Yas Marina in time to be eligible to race with Mercedes on Sunday.
"There are still some question marks over who will be in the car this weekend in Abu Dhabi," Wolff said.
"Lewis's condition is improving, but we won't know until closer to the time if he will be driving.
"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."
While Mercedes will wait to make a final call that could come as late as Saturday afternoon, stand-in George Russell is listed for the team in Thursday's FIA press conference, while Jack Aiken is listed for Williams.
Looking back on last weekend's pitstop disaster that saw Mercedes' crews confuse their drivers' tyre allocations, Wolff said measures had been put in place to avoid a repeat of the blunder.
"We head into the final race of the season looking for redemption after a disappointing race in Sakhir, where both George and Valtteri lost the opportunity to win," Wolff said.
"The pit stop problem has uncovered an underlying problem with our intercom, and we've put measures in place, both technically and in the way we operate, to make sure it doesn't happen again."
Wolff revealed ahead of this week's season finale that a surprise was in store for the Black Arrows squad's team members at Yas Marina.
"We'll be running a slightly different livery on Saturday and Sunday featuring everyone's name on the car to honour the huge commitment and determination from everybody in Brixworth and Brackley," Wolff explained.
"Everyone has pushed hard this year, raising the bar through this massively intense season, and we hope this gesture goes some way in showing the appreciation we have for everyone involved.
"Abu Dhabi is always a fun race weekend with the end of season vibe and an interesting track for the engineers to tackle.
"The atmosphere will be slightly different this year with the COVID-19 control measures, but we're as motivated as ever to end the season with a strong result and head into the winter break on the right foot."