Hülkenberg has already deputised on two occasions for the team after Perez was forced out of the British and 70th Anniversary Grands Prix, and Stroll missed the last race at the Nürburgring.
For the Eifel GP, Hülkenberg was fortunately only an hour's drive away from the circuit in Cologne when a call was made after Stroll pulled out on Saturday morning due to an upset stomach.
On this occasion, Hülkenberg is in Portimão for the Portuguese GP should either Perez or Stroll be forced to withdraw, notably the latter who has spent the last 10 days in self-isolation after testing positive for Covid-19 on Monday, October 12.
"Yes, Nico is here, and I think other teams have also opted to bring reserve drivers for the first time. It just makes sense to have reserve drivers," said Racing Point team principal Otmar Szafnauer.
"He [Stroll] had a negative test coming into this weekend. The probability of now giving a positive is low. Is it zero? I don't know, I don't know that much about it, but it's low.
"Nico is here as a precaution, but I'm confident Lance will be in the car this weekend."
Szafnauer, meanwhile, has launched a vigorous defence of his team's Covid-19 testing programme in light of the positive test given by Stroll, who had been feeling unwell since the Russian GP.
Although Stroll undertook a handful of tests in between that race and the Eifel GP, and even consulted with his own private physician in Switzerland in between the two events, Szafnauer is adamant his team did nothing wrong.
"We test more than any other business on the planet, not just Formula 1 teams," added Szafnauer.
"I test every employee twice a week at the factory. We have done more than 15,000 tests, and we've had six positives.
"We take this virus more seriously than anybody. We test all of our staff upon arrival from a grand prix so they have peace of mind when they go home that they didn't pick anything up."
With regard to the protocols around Stroll, in particular, Szafnauer added: "His [Stroll's] doctor said 'No, it's not a Covid symptom'. I'm not a doctor.
"What I can logically think about is he had these symptoms after Russia, is when it started really, and after Russia we tested him upon arrival - as we always do - and he was negative. Then we had a pre-event test and he was negative.
"You could see how somebody could say that symptom and Covid are not linked. We've tested you multiple times for Covid, you've had an upset stomach, but you're negative.
"Could he have had an upset stomach and not Covid, and they're not linked? Could very well be."
Szafnauer has confirmed team owner Lawrence Stroll, who was not present at the Nürburgring, also tested positive at the same time at his son.
"Lawrence went to Aston Martin and was there on Thursday [before the grand prix] and he tested, and that Thursday test came back negative on Friday," said Szafnauer.
"And then when Lance landed [in Canada on Sunday] and tested, Lawrence tested at the same time, and then both tests came back positive, despite not being together."
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