Max Verstappen believes that Nico Hulkenberg could face a "steep learning curve" when he substitutes at Aston Martin for the Bahrain Grand Prix.
The reserve driver will fill in for Sebastian Vettel over the opening race weekend of the season, with Vettel having tested positive for COVID-19.
Hulkenberg last took part in a Grand Prix weekend in 2020, when he first stepped in for Sergio Perez in back-to-back races at Silverstone due to the Mexican contracting coronavirus.
He then filled in for Lance Stroll later that year at the Eifel Grand Prix, when the Canadian also tested positive for COVID-19.
This time, though, Hulkenberg faces the challenge of getting behind the wheel after drastic changes to the sport's regulations.
Verstappen predicts "tough" weekend for Hulkenberg
Verstappen has spoken to Hulkenberg since the news of his return emerged, and says that the German is feeling "excited" about driving again.
However, given his time away from the track, the weekend could be a challenging one for him, according to Verstappen.
"I don't know how much he worked out!" Verstappen joked to select media including RacingNews365.com about Hulkenberg's fitness.
"Luckily, this track is not the most physical out there, but if you haven't really done a lot in terms of F1 fitness levels, it's still, I think, going to be quite a tough one.
"I already spoke to him this morning and I think he is of course very excited to drive, but he also doesn't know the car, so it's going to be quite a big learning curve for him."
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Challenge of adapting to 2022 F1 car
Hulkenberg also faces a disadvantage in being the only driver on the grid this weekend to have not been behind the wheel during either of the pre-season tests in Bahrain and Barcelona.
Even Kevin Magnussen - whose return to Haas was only announced one week ago - had some running time in the VF-22 in Bahrain last week.
"The cars are completely new to him, [and] he hasn't driven the [18-inch] tyres," Verstappen added.
"And to only have the free practice sessions while everyone really had a good run [in testing], except maybe Kevin, of course.
"It's going to be tough, for sure."
Drivers may discuss COVID-19 protocols
News of Vettel's positive COVID-19 test comes after Daniel Ricciardo also tested positive for the virus last week, forcing him to miss all three days of testing in Bahrain.
When asked whether drivers should still be allowed to race with COVID in countries that no longer have restrictions in place - such as the United Kingdom - Verstappen admitted that it is something worth discussing.
"I do think we need to look into it, because when you test positive, well, you can test positive with any virus," the Red Bull driver explained.
"So, at one point, I do think we need to ease off on the positive case [meaning that] you cannot race because, I think nowadays, in most countries - when you are vaccinated, anyway - you might get ill, but it's not life-threatening anymore, for most of the people, luckily.
"And of course you can take safety measures, even if you are positive, you might stay away from people. But [it's] something maybe us drivers also need to look into, what we can do with the FIA in the future."
On whether the topic might be brought up in the GPDA (Grand Prix Drivers' Association), Verstappen added: "It's something, maybe, [that could] come up. We haven't talked about it yet, but also we just found out about Seb."
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