Indeed the Briton was an alarming 0.709 seconds slower than Vettel and ended up behind not only the German but Kimi Raikkonen, in the sister Ferrari, and his Mercedes team-mate Valtteri Bottas, too.

But Vettel believes Hamilton and his Mercedes team, who have led every lap of each of the three races staged at the Sochi Autodrom, were sandbagging and will have plenty more in the locker for qualifying and latterly Sunday's race, too.

Hamilton, however, scoffed at Vettel's remarks.

"I don't know why they would suggest that," he said. "That's just Sebastian trying to blow smoke our way. Those guys are very quick.

"If we get our tyres working we can get closer, and the gap is still very, very close, but we are just not as quick as we need to be.

"We are not the quickest, and of course I want to be, but rather than get concerned about it I just put my energy towards trying to figure out how we can improve.''

Hamilton, 32, has won twice in Russia and will be desperate to bounce back in his quest to win his fourth title following his defeat to Vettel at the Sakhir Circuit a fortnight ago.

Yet it was Vettel, and his ever-impressive resurgent Ferrari team here, who appeared on course to strengthen their grip on the new season after a dominant display.

First, his Ferrari team-mate Raikkonen posted the fastest lap in opening practice before Vettel soared to the top of the timesheets during the day's second running.

Vettel set a best lap of one minute and 34.120 seconds - the fastest ever seen at this 3.1-mile circuit which runs through the Olympic Park, the site of the 2014 Winter Games - to lead a Ferrari one-two.

But Vettel said: "I think Mercedes will be fine. It is a circuit that suits them so they will be strong in qualifying. For sure they didn't show everything today and they didn't get a lap together, so the gap you see is artificial."