Sebastian Vettel keeps Ferrari on top in final Russian GP practice

The German clocked a 1m34.001s on the ultra-soft Pirelli tyres, 0.337 seconds quicker than team-mate Kimi Raikkonen.

Valtteri Bottas was Ferrari's closest challenger, 0.363s adrift in third and two tenths ahead of Mercedes team-mate Lewis Hamilton.

Ferrari and Mercedes set out on the ultra-soft compound early in the session as they battled to understand how to use their tyres in the most effective away ahead of qualifying.

After the first runs, Hamilton was quickest, 0.105s faster than Vettel with Bottas third, a further tenth-and-a-half adrift.

With 20 minutes to go, Mercedes headed back out first with Bottas going quickest with a 1m34.681s on his second timed lap, having done a build-up lap to get heat into the tyres.

Hamilton was on course to go quicker, using the same warm-up strategy, but made a series of mistakes in the final sector.

Raikkonen then put Ferrari top with a 1m34.338s before Vettel clocked the fastest-ever lap at Sochi with a 1m34.001s.

He was on course to go even quicker and break the 1m34s-barrier, but lost two tenths in the final sector.

Both Mercedes drivers improved on their second flying laps, but they stayed in third and fourth respectively.

Red Bull's Max Verstappen was best of the rest in fifth, but he was 1.451s off the pace, a few thousandths clear of Felipe Massa.

Verstappen's team-mate Daniel Ricciardo, who momentarily stopped on track in the closing minutes of the session before getting going again, was seventh ahead of Nico Hulkenberg.

Carlos Sainz Jr and Kevin Magnussen completed the top 10.

Jolyon Palmer was the only driver who failed to set a time with his Renault team deciding to change his engine ahead of qualifying.

That came after its mechanics worked well into the night to complete a precautionary chassis change for the Briton after an exhaust leak on Friday.

PRACTICE THREE RESULTS: