Lewis Hamilton was fastest in second practice for the Russian Grand Prix on Friday as his championship rival Sebastian Vettel finished only fifth.

Hamilton, who holds a 40-point lead over Ferrari driver Vettel with just six rounds remaining, ended up 0.199 seconds clear of his Mercedes team-mate Valtteri Bottas at the Sochi Autodrom.

The Red Bull duo of Max Verstappen and Daniel Ricciardo - both due to start Sunday's race from the back of the pack following grid penalties for exceeding the number of allocated engine parts - placed third and fourth respectively.

Vettel, who had been quickest in the opening running, was half-a-second down on Hamilton, while his Ferrari team-mate Kimi Raikkonen finished sixth, one second off the pace.

Hamilton was mysteriously off-colour at this venue last season, but the world champion will be encouraged by his performance in practice.

The Brit was third at the conclusion of the opening session before then soaring to the top of the time sheets with a best lap of one minute and 33.385 seconds later in the day.

With the season reaching its climax, Vettel surely must finish ahead of Hamilton on Sunday to prevent the Mercedes driver from marching to a fifth title.

But the German endured a scrappy afternoon in Sochi, spinning at the right-handed 13th turn, before finishing behind both the Mercedes and Red Bull cars.

Traditionally Ferrari hold a little in reserve on Friday, and Vettel, who has driven the only non-Mercedes car to start this race from pole position, will hope his pace improves in qualifying on Saturday.

Sergio Perez finished seventh for Force India, 1.7secs slower than Hamilton as Toro Rosso's Pierre Gasly, the other Force India of Esteban Ocon and Sauber's Marcus Ericsson completed the top 10.

Earlier, British teenager Lando Norris, who will be promoted to McLaren's race team next year, deputised for Fernando Alonso in opening practice.

The 18-year-old finished 13th, three places and one tenth ahead of the outgoing Stoffel Vandoorne in the other McLaren.

Alonso, the double world champion who is calling time on his Formula One career at the end of the year, was back in the car for the final session of the day, but finished a lowly 17th.

Sergey Sirotkin, the only Russian racing in the field this weekend, finished with the penultimate time ahead of his Williams team-mate Lance Stroll.