Paul Di Resta is ready to race for McLaren should Mercedes Formula E drivers Stoffel Vandoorne and Nyck De Vries not be avaliable.
McLaren and Mercedes are sharing reserve drivers for 2021, however calendar clashes in May between Formula 1 and Formula E would leave both teams without a driver who is ready to step up if needed.
Di Resta has agreed a deal with McLaren to be a potential reserve driver, as he did at last year's 70th Anniversary Grand Prix.
"Our main focus is on this agreement that we are having with with Mercedes," McLaren team boss Andreas Seidl told RacingNews365.com and other select members of the press.
"As you know also with what we would have had in place last year in Silverstone, we have a good relationship also with Paul di Resta, who is also in possession of a super licence.
"So we have an agreement with him as well in order to jump in if the requirement is there. So we're prepared for different scenarios."
Seidl was asked whether Nico Hulkenberg would be an option for McLaren if Daniel Ricciardo or Lando Norris were unable to race.
"Again, in the end, we are depending on Mercedes," Seidl explains. "We simply have to follow what Mercedes is putting in place for the different weekends. But our main focus is clearly on Stoffel and Nyck."