(AFP) - Nico Rosberg topped the times ahead of his Mercedes team-mate and defending three-time world champion Lewis Hamilton in Friday's opening free practice for this weekend's Russian Grand Prix.
The 30-year-old German clocked a best lap in 1min 38.127sec to outpace the 31-year-old Briton by seven-tenths of a second.
Four-time champion German Sebastian Vettel was third-fastest for Ferrari ahead of his team-mate, the Finn Kimi Raikkonen, the leading teams proving again that they have established themselves at the front of the field.
For Rosberg, it was confirmation that he can maintain his current supremacy over Hamilton after winning six races in succession, including three last season - a run that has lifted him 36 points clear at the top of the title race.
Brazilian Felipe Massa was fifth for Williams ahead of Australian Daniel Ricciardo who tested his Red Bull team's new 'Aeroscreen' driver cockpit protection device on his opening installation lap without problems.
Finn Valtteri Bottas was seventh in the second Williams ahead of local hero Daniil Kvyat in the second Red Bull after a relatively unexceptional session run in dry and bright conditions at the Sochi Autodrom, a track built in the former Olympic Park on the shores of the Black Sea.