Lewis Hamilton has not ruled out an engine change at this weekend's Brazilian Grand Prix, which would trigger a grid penalty.
Red Bull advisor Helmut Marko revealed that he had heard "rumours" of Hamilton moving on to a fifth Internal Combustion Engine of the season in Sao Paulo.
A new engine would give Hamilton a five-grid place penalty for Sunday's race, putting him on the back foot.
"I can't really comment at the moment," Hamilton told media, including RacingNews365.com. "I don't know. I don't think the engines have even arrived this morning.
"So as far as I'm aware currently, my engine is fine. But I'll find out obviously, later on. We've not even done engineering meeting yet."
An uphill battle awaits
Hamilton trails championship leader Max Verstappen by 19 points following the Dutchman's victory last weekend in Mexico City.
The Mercedes driver has won just one of the last eight races and is adamant Red Bull have had the best car this year.
Hamilton was asked how steep of a task he and the team have to win in Brazil.
"I would imagine as steep as it can be," said Hamilton. "I think their pace was phenomenal in the last race.
"They've had a strong car all year. They've had the strongest car all year, you can tell obviously. I think we've done as good as we think we could.
"We will definitely be pushing this weekend to see if we can squeeze any more out of the car. Last time here [in Brazil] they were incredibly strong.
"We anticipate again they'll be very hard to beat this weekend."
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