Lewis Hamilton admits there is still some "mystery” behind the Mercedes Formula 1 team’s sudden drop off in performance in recent races in Mexico and the United States.

Hamilton wrapped up his fifth world championship title despite a distant fourth-place finish in Mexico City, one position ahead of lapped teammate Valtteri Bottas, as Mercedes struggled with excessive tyre wear compared to its rivals.

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It followed similar issues at the previous race in Austin, leading to suggestions Mercedes’ decision not to run its controversial wheel rim design at both events was a factor in the team’s performance dip.

Mercedes refuted the claims and team boss Toto Wolff later said he was confident his side had made progress in understanding its recent challenges heading into this weekend’s Brazilian Grand Prix, though Hamilton reckons there is more work to be done.

“I think some of it is still a mystery but I think there are a lot of areas that we have understood,” Hamilton said.

“We are coming to another circuit that is quite hard on tyres, Brazil is always quite tough in that area but we have not been terrible here. I think this track does work quite well with a more nimble, shorter car.

“I’m hoping this weekend we can get the car into the right place and fight the guys, and the Red Bulls and Ferraris who have seemed to come back more into shooting range.

“Red Bull’s dominance at the last race was impressive and I’m sure they will be quick this weekend as well, as will Ferrari.

“It is going to take everything and more - we will have to throw everything at it, including the bathroom sink.”

Bottas said he had been encouraged by the promising steps made by Mercedes after visiting the team’s Brackley base in the gap between Mexico and Brazil.

“The team worked really hard to find the answers for that, quickly,” Bottas explained.

“I went to the factory as well, had a really interesting meeting about that, seeing how we were really able to track those issues and where all of them started from.

“It’s really how we’re managing the car, many mechanical things and so on. We know the mistakes we have made and we’re hoping not to repeat them.”