Nico Rosberg pipped Lewis Hamilton to lead the first practice session at the Russian Grand Prix.
The German's 1:42.311 was just .065 of a second clear of his Mercedes team-mate as the drivers sampled the new Sochi Autodrom for the first time.
McLaren looked strong throughout with Jenson Button leading before the Silver Arrows took over, but the 2009 champion hung on to third with his team-mate Kevin Magnussen fifth.
The main aim of the morning was to learn and understand the new street circuit around Sochi's Olympic park.
First impressions are of a circuit that will certainly suit those with the Mercedes, and therefore more powerful, power units with the long straights and mostly slow corners suiting the strengths of the British-made V6 turbo engine.
As was expected, the new circuit offered very low grip levels with the F1 cars the first to lay some rubber down on the very smooth track surface.
Under braking, particularly at the end of the two long straights, many drivers went wide across the run-off areas.
There were a few parts of the track that offered a few surprises. The long turn three (or four depending on which diagram you look at) was not totally flat as drivers lifted halfway around the U-shaped turn, however, as grip levels and confidence improve we can expect more drivers to keep the throttle wide open particularly in qualifying.
The other surprise came at the very tight left, right chicane at turns 15 and 16. A small brow on the apex to the first left-hander saw several drivers lock up and be pushed wide making the right much tighter than it otherwise would.
Mercedes power shines
As I mentioned the circuit certainly looked to be one that would suit the Mercedes-powered teams and so it would prove with only Fernando Alonso's Ferrari denying an all Mercedes backed top six.
McLaren look strong, as do Force India with Sergio Perez managing to claim sixth in his VJM07.
The lack of medium and high-speed turns will really help the customer teams and while Williams were only 10th and 11th, they should be the team expected to take the 'best of the rest' slot behind the works Mercedes team.
A new Russian race, and an impressive start for local hero Daniil Kvyat. The 20-year-old Toro Rosso driver was near the top of the standings throughout the opening session eventually finishing seventh only eight tenths slower than the Mercedes.
His team-mate Jean-Eric Vergne endured a few lock-ups at turn two but was also in the top 10 in ninth as both the junior Red Bull drivers beat their bigger brothers as Daniel Ricciardo an Sebastian Vettel were 12th and 14th respectively.
Another Russian, teen Sergey Sirotkin, made his long awaited F1 debut for Sauber. The man from Moscow eased his way into his first official session and was an impressive 17th by the end only four tenths closer than full-time driver Adrian Sutil.
Marussia honour Bianchi
The session was the first since Jules Bianchi's serious crash at Suzuka just five days ago, and as the sport prays for and supports the critical but stable Frenchman, his team Marussia have decided to only use one car in Sochi this weekend.
While reserve Alexander Rossi was considered to drive in place of Jules, the team decided this would be its way of respecting the Frenchman with his car sat in its usual place in the garage with the No. 17 on the front.
Their sole entrant Max Chilton admitted it would be a very difficult weekend for him and all the team without Bianchi present.
"I don't know how to put into words how truly devastated I am by what has happened to Jules," he said in a team statement.
"The support from the F1 family has been incredible and all we can do is be there to support Jules' family at this difficult time.
"It is going to be a very emotional weekend for the whole team, but we will try to get through it and keep praying for Jules."
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