It was another difficult day at the office for Sebastian Vettel at the Russian Grand Prix, but he insists a fifth Formula 1 title in 2018 remains possible.

The Ferrari driver fell 50 points behind runaway leader Lewis Hamilton after finishing third in Sochi, as Mercedes used team orders to give the Briton a fifth win in six races.

To make matters worse, Hamilton stamped home his current advantage over Vettel by producing a bold move on the German on track after falling behind in the pit-stop phase before the controversial decision by his team.

With just five races left to go, it would appear not even Everest could describe the mountain faced by the 31-year-old, even so, he believes it would take just one twist at one of the more unpredictable races to come for the pendulum of momentum to change.

"I still believe in our chances, yes," he declared after Sunday's race.

“I’m clever enough, I wasn’t a genius in maths but I was clever enough to pay attention to make out for myself that it’s not getting easier if we lose points.

"We had to be third and settle with that for today," he acknowledged.

"But who knows, it takes one DNF [retirement] and then all of a sudden things look different – ideally two! Which I’m not wishing on Lewis but you never know what happens.

“So we need to stay on top of our game which maybe we haven’t been completely this weekend: make sure that from where we are now we focus on winning the last races.”

Indeed, while there are only five races left to go three of them could be potentially tricky for Hamilton with this weekend's event in Japan and the Brazilian Grand Prix at Interlagos both well known for producing dramatic, season-altering moments.

Then there's the Mexican GP where Red Bull are expected to be very competitive and could well put some more cars between Vettel and his main championship rival.

With Sochi very much considered a Mercedes stronghold, having now won every race there since it joined the calendar in 2014, Ferrari boss Maurizio Arrivabene believes the technical challenge of Suzuka will offer the clearest example of whether the fight is still on.

“Despite all our efforts to find the ideal set-up, neither on Saturday nor in the race were we competitive enough to worry our closest rivals," he said of the weekend in Russia.

“Compared to the way we performed at other circuits, something was missing here and so we were unable to reduce the points gap.

“On paper, the next race in Japan should have very similar characteristics to the one at Silverstone, so in Suzuka, we will get a more precise indication as to the potential of our car.

“If it goes well, we will know that, despite the difficult situation in terms of the classification, we still have the right weapons with which to fight all the way to the very end.”