Vettel leads Ferrari one-two in Sochi

Sebastian Vettel has led a Ferrari one-two in Russian GP practice with the Italian team appearing to have a clear edge over champions Mercedes.

Formula One frontrunner Sebastian Vettel has led a Ferrari one-two in Russian Grand Prix practice. (AAP)

Ferrari remains quickest in Saturday's final practice for the Russian Formula One Grand Prix, with Sebastian Vettel and Kimi Raikkonen topping the timesheets.

Vettel posted a best 1 minute 34.001 seconds around the Sochi Autodrom track, wth Raikkonen 0.337 seconds behind.

Their performance gives Ferrari strong hopes of a first pole position from qualifying since the 2015 Singapore GP.

The Ferrari pair split the honours in first and second practice on Friday and though Mercedes gained some pace in the third session, they could not close the gap completely.

Valtteri Bottas took third with Lewis Hamilton in fourth once more, more than half a second adrift.

Australia's Daniel Ricciardo was eighth in the practice session in his Red Bull in a time of 1:35.830.

Vettel, who won in Australia along with Bahrain, has 68 points in the championship standings, while Chinese GP winner Hamilton is on 61 and Bottas on 38 ahead of Sunday's race.