McLaren has recruited Paul di Resta as its official reserve driver for this weekend's 70th Anniversary Grand Prix at Silverstone.
The former Force India charger, who subbed for Felipe Massa at Williams in 2017, underwent a seat fitting at Woking on Wednesday as a matter of precaution.
McLaren has an agreement with Mercedes to call upon its reserve drivers in the event that either Carlos Sainz or Lando Norris should become unavailable.
But Stoffel Vandoorne is committed to Mercedes' Formula E efforts in Berlin while Esteban Gutierrez does not currently hold a proper superlicence.
While McLaren isn't forecasting any issues with its drivers, the case of Racing Point's Sergio Perez, who tested positive for the coronavirus last week and was ruled out of the British Grand Prix, teams are setting up contingency plans just in case.
"As we have previously confirmed, we have an arrangement with Mercedes to use their reserve drivers in the event either Carlos or Lando are unable to race," McLaren said in a statement.
"With Stoffel Vandoorne unavailable due to his Formula E commitments and Esteban Gutierrez currently not eligible for a superlicence, Paul di Resta will be our standby driver this weekend.
"Paul carried out a seat fit at the MTC this morning in compliance with the FIA COVID-19 protocols but will not be in close contact with the McLaren race team unless needed.
"Paul will continue his duties with Sky Sports F1 this weekend as planned."
Regarding the option of putting Fernando Alonso on stand-by, the former McLaren driver is on his way to Indianapolis, and therefore not available as a potential reserve.
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