Red Bull’s Max Verstappen was a surprise pacesetter as he headed Ferrari’s Charles Leclerc in second practice at the Russian Grand Prix.
The Dutchman, who has a five-place grid penalty, was 0.335 seconds ahead of Leclerc. Mercedes’ Valtteri Bottas was third, 0.646secs off the pace.
Championship leader Lewis Hamilton was 0.152secs slower than Bottas in fourth.
Ferrari’s Sebastian Vettel was 0.704secs off team-mate Leclerc, after errors led to a series of aborted laps.
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Both Hamilton and Vettel did not appear as comfortable as their team-mates on their single-lap qualifying-simulation runs.
Red Bull had struggled in Singapore last weekend, but they believe post-race analysis suggested they had made a mistake with the set-up.
Their pace in Russia on Friday suggests they are back to the more competitive level they had shown during the summer.
But they are poised for a difficult weekend because both Verstappen and team-mate Alexander Albon have a five-place grid penalty for using too many engine parts.
Meanwhile, Ferrari’s pace bodes well for the Italian team, who were unexpectedly quick in Singapore following a major aerodynamic upgrade to their car.
Ferrari have won the last three races and Hamilton said on arriving in Russia that, following their upturn in form, he believed Mercedes would not be favourites for any of the remaining races.
Bottas is always strong in Russia, where he has never been out-qualified by a team-mate, and he appeared to have an edge on Hamilton throughout the day.
While at Ferrari, Vettel had to abort his first two attempts at a qualifying run, before finally managing to set a time at his third attempt.
Best of the rest was Toro Rosso’s Pierre Gasly, who narrowly avoided colliding with team-mate Daniil Kvyat when the Russian did not see him after emerging from the pits.
Racing Point’s Sergio Perez was seventh ahead of Renault’s Nico Hulkenberg, the second Racing Point of Lance Stroll and Red Bull’s Alexander Albon.
The Anglo-Thai had a difficult day. He missed some of the session because of floor damage and when he did emerge to set a fast lap was more than two seconds slower than Verstappen.
“It has been a day of discovery and exploring,” said Hamilton. “Started off not too bad and then it just didn’t really improve whereas the others made some big progressions.
“We’re losing 0.8secs or something to the Ferraris on the straights. We have just been trying to figure out how to improve the car, but it’s not an easy task.
“It is going to be a tough day tomorrow but I hope it’s going to be raining – I heard it’s going to be raining.”