Ferrari were in sparkling form on Friday afternoon, with Sebastian Vettel and Kimi Raikkonen comfortably fastest in FP2 ahead of the strangely subdued Mercedes drivers.
Top honours went to Vettel, who ended the session fastest with a best lap time of 1:34.120s, over quarter of a second faster than his team-mate.
Having topped the morning times, it was Raikkonen who had been quickly up to speed in the afternoon practice.
The first driver to try ultrasofts, he displaced Lewis Hamilton from the top of the timesheets just before the half hour mark. His time of 1:34.721s was a second faster than Hamilton’s earlier effort, and already a new track record for Sochi Autodrom.
Both Raikkonen and Vettel further improved their times on subsequent laps, proving the ultrasoft’s durability in Russia. Vettel eventually came out of this private battle on top, and his flying lap was to remain the fastest of the day.
Valtteri Bottas and Lewis Hamilton did close the gap a little, but both Mercedes remained around seven tenths off Vettel’s benchmark.
The two Red Bull drivers Max Verstappen and Daniel Ricciardo were almost a further second in arrears in fifth and sixth, with Williams’ Felipe Massa a distant seventh.
Attention subsequently turned to long-run simulations as teams concentrated on gathering further data on tyre durability.
The Sochi circuit continued to catch out several drivers, with both Mercedes drivers among those to run wide and off-track at turn two.
Verstappen had a scare at turn five midway through the 90-minute session, running very wide and lucky not to graze the wall.
There were plenty of further lock-ups resulting in flat-spotted tyres. Daniil Kvyat spun at turn 13 early in the session, with Romain Grosjean going likewise at the last corner in the final half hour. Both cars were able to recover and get going again.
Less fortunate was Verstappen, whose car lost power with 20 minutes remaining in the session. He came to a halt exiting turn 16 just before pit entry, resulting in local waved yellows while the marshalls recovered the RB13.
Stoffel Vandoorne also lost time at the start of FP2 while McLaren fitted another new Honda engine. He has a 15 place grid penalty for Sunday’s race as a result of taking his fifth MGU-H and turbocharger of 2017.