In the three Russian Grand Prix held to date, a Mercedes has led every lap at Sochi. But Lewis Hamilton fears that this might all be about to change this weekend.
Ferrari were comfortably faster than anyone else in Friday's practice session, leaving Hamilton acutely aware there's work to be done.
"There is no such thing as a guarantee for winning, not even here," he told the official Formula 1 website.
"If we win this weekend then it will be because we have worked very hard for it," he added. "Not because of the opinion that people have that this is a ‘Mercedes track.' We have to earn it fair and square.
"Obviously from what we’ve seen today we have to find time on the track for tomorrow," he admitted.
"We have to find some changes that will help us get back to the strength that we had, and that Ferrari obviously has at this very moment. I am sure that we will achieve it."
Hamilton also struggled for pace in Bahrain, but he said that the problems in Sochi were quite different.
"This is a different track to Melbourne and Bahrain, so everything is blown wide open for Sunday," he said.
"One of our paramount aims will be to get more temperature into the rear tyres," he continued. "This track has a special tarmac where tyre degradation is not so much the issue - getting the temperature into the rear tyres is.
"After analysing the data this evening we will discuss how to go about the setup We definitely have to change things to be able to fight back tomorrow. And more importantly, on Sunday."
GALLERY: All the pictures from Friday in Sochi
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