Championship leader Sebastian Vettel led a Ferrari 1-2 as the team finished comfortably clear of the pack during second practice for the Russian Grand Prix.
Vettel and team-mate Kimi Räikkönen traded quickest times on the purple-banded Ultra Soft tyres at the Sochi Autodrom, before Vettel moved ahead with a 1:34.120, over a second faster than last year's best lap at the venue.
Vettel's time was 0.263s up on Räikkönen, as the pair held a sufficient gap back to rivals Mercedes, with Valtteri Bottas and Lewis Hamilton unable to match Ferrari’s pace.
Bottas’ best lap was 0.670s down on Vettel’s fastest, while Hamilton had a scruffy session, having to abort a couple of his Ultra Soft attempts.
Hamilton went wide through the Turn 4 right-hander on his first run and encountered Pascal Wehrlein on the approach to Turn 13 later on, winding up 0.709s adrift of Vettel.
Red Bull emerged as the third-best team once more, adrift of Mercedes but ahead of a closely-contested midfield group, as has been the case for much of the opening part of the season.
Max Verstappen finished fifth, 1.4s behind Vettel and 0.7s down on fourth-placed Hamilton, having recovered from a wide moment at Turn 5, with Daniel Ricciardo over three-tenths further back in sixth.
Verstappen, though, was unable to complete the session after pulling to the side of the circuit between Turns 16 and 17 with 20 minutes remaining, due to a suspected loss of power.
Ricciardo held 0.4s advantage back to Felipe Massa, who led the midfield charge in seventh, with just half a second covering the Brazilian, Renault’s Nico Hülkenberg, Haas’ Kevin Magnussen and the Force India pairing of Sergio Pérez and Esteban Ocon.
McLaren’s Fernando Alonso and Renault’s Jolyon Palmer finished a tenth behind Ocon in 12th and 13th, with the duo themselves split by just 0.006s.
Romain Grosjean took 14th, and spun at the final corner during his long-run on Ultra Softs, amid rear locking on his Haas, prompting complaints from the Frenchman.
Toro Rosso pair Carlos Sainz Jr. and Daniil Kvyat were 15th and 16th, Kvyat having looped his STR12 around Turn 13 early on in the session, while the aforementioned Wehrlein took 17th.
Stoffel Vandoorne finished a lowly 18th for McLaren, following a power unit change between sessions, which has led to the Belgian being hit by a 15-place grid penalty.
Williams rookie Lance Stroll made an error exiting Turn 7 and placed 19th, his best time set on the Super Softs, with Marcus Ericsson at the back in 20th spot.
