Nico Rosberg made an ominous start at the Russian Grand Prix when he was almost three-quarters of a second quicker than Mercedes team-mate Lewis Hamilton in the first practice session on Friday.
Rosberg has won the first three races of 2016 to extend his run of victories to six stretching back to last season and there were no signs that the German's dominance will end this weekend in FP1.
The Formula One world championship leader laid down yet another marker when he clocked one minute 38.127 seconds on supersoft tyres at the Sochi Autodrom circuit.
World champion Hamilton, who has won both races since the Russian Grand Prix returned to the F1 calendar, was 0.722secs slower as he sets about trying to close the 36-point gap Rosberg has opened up in the early stages of the season.
Ferrari duo Sebastian Vettel and Kimi Raikkonen were third and fourth respectively, trailing Rosberg by more than a second, with Felipe Massa fifth-fastest for Williams.
Daniel Ricciardo gave a debut to the Aeroscreen, which Red Bull trialled as a potential solution for head protection on an installation lap to test visibility through the screen while at the wheel.
Ricciardo was sixth-quickest in FP1 after the device was removed, while team-mate Daniil Kvyat was down in eighth in his home race.
1. Nico Rosberg (Mercedes) 1:38.127
2. Lewis Hamilton (Mercedes) 1:38.849
3. Sebastian Vettel (Ferrari) 1:39.175
4. Kimi Raikkonen (Ferrari) 1:39.332
5. Felipe Massa (Williams) 1:39.365
6. Daniel Ricciardo (Red Bull) 1:39.650
7. Valtteri Bottas (Williams) 1:39.802
8. Daniil Kvyat (Red Bull) 1:40.218
9. Sergio Perez (Force India) 1:40.287
10. Carlos Sainz (Toro Rosso) 1:40.654