Lando Norris was feeling under the weather on Thursday in Sao Paulo and was excused from media duties at Interlagos, while McLaren has reportedly put Mercedes reserve Nyck de Vries on standby, just in case.
A tweet from McLaren suggested that Norris was suffering from food poisoning, with doctors ordering the Briton to rest at his hotel on Thursday.
However, the papaya squad expects Norris to be up and running on Friday as scheduled.
But should the McLaren charger remain ill, de Vries - who will race for AlphaTauri next season but who remains contracted to Mercedes as the German outfit's reserve driver - would sub for Norris this weekend.
Should the Dutchman take to the track with McLaren at Interlagos, it would be the fourth team for which de Vries has driven this season.
The 27-year-old enjoyed FP1 sessions with Williams in Barcelona, with Mercedes at Paul Ricard and with Aston Martin at Monza.
But Alex Albon's sudden unavailability at the Italian Grand Prix due to appendicitis led to de Vries making his F1 race debut at the Temple of Speed with Williams.
De Vries' remarkable performance and ninth-place finish a Monza compelled Red Bull to snap up the rookie as Pierre Gasly's replacement at AlphaTauri.
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