Kimi Raikkonen topped the times for Ferrari ahead of fellow-Finn Valtteri Bottas of Mercedes in Friday's opening free practice for this weekend's Russian Grand Prix.
The 2007 world champion clocked a best lap of one minute and 36.074 seconds after an hour of a desultory 90-minutes' action.
That lap lifted him 0.045 seconds clear of Bottas, who secured his maiden pole position at the Bahrain Grand Prix earlier this month, and six-tenths beyond third-placed three-time champion Briton Lewis Hamilton in the other Mercedes.
Championship leader German Sebastian Vettel was fifth for Ferrari behind Dutch teenager Max Verstappen of Red Bull, the four-time champion delivering one dramatic spin as he slithered in pursuit of the pace-setters.
Hamilton, on softs, was the early pace-setter before Bottas, on super-softs, took over at the top shortly before the hour mark, but there was precious little serious action from most teams.
Bottas' lap moved him half a second clear until, with 29 minutes remaining, Raikkonen clocked his lap to move a tenth of a second ahead of his compatriot for Ferrari.
Frenchman Sebastian Ocon then lost the engine cover on his Force India car, the errant debris forcing a brief red-flagged stoppage before Vettel rejoined the fray without making much impact, other than a major spin at Turn 15, but without damage.
Australian Daniel Ricciardo, in the second Red Bull, worked his way up to sixth ahead of Mexican Sergio Perez of Force India, Brazilian Felipe Massa and his Williams team-mate rookie Canadian teenager Lance Stroll and Ocon.