Racing Point's Lance Stroll missed final practice for the Eifel Grand Prix on Saturday with speculation that Nico Hulkenberg could stand in for the unwell Canadian in qualifying and Sunday's race at the Nuerburgring.
Racing Point said on Twitter that Stroll, whose father Lawrence owns the team, was not feeling 100% and would sit out the session.
"His condition will be assessed after the session to evaluate whether he is fit to drive, at which point the team will confirm plans for Quali," the team added.
Germany's Hulkenberg stood in for Stroll's team mate Sergio Perez in August when the Mexican tested positive for Covid-19 and missed two races for the Mercedes-powered team.
Hulkenberg was at the Nuerburgring, arriving earlier on Saturday for broadcasting commitments.
He would be eligible to take part in qualifying if granted a dispensation by the governing FIA and depending on the result of a COVID test.
Mercedes' Belgian reserve Stoffel Vandoorne was also at the circuit.
Mercedes dominated the session, the first of the weekend after bad weather wiped out Friday's practice, with Finland's Valtteri Bottas 0.136 quicker than six times world champion and overall leader Lewis Hamilton in cold conditions.
Bottas's best time was one minute 26.225 seconds.
Ferrari's Charles Leclerc was third fastest and Red Bull's Max Verstappen fourth.
The fog that prevented the medical helicopter from taking off on Friday lifted, with the FIA putting in place measures to ensure track action could go ahead if the weather turned bad again.
A spokesman said a landing area had been created some three km from the circuit at a lower altitude that is usually free of cloud cover. Any injured person could then be driven to the helicopter for transfer to hospital.