Lewis Hamilton says his Mercedes W05 Hybrid felt good during Friday practice for the Russian Grand Prix in Sochi, but acknowledges that former team McLaren will be close.
Hamilton set the pace at Sochi Autodrom, 0.8s clear of Kevin Magnussen, with former team-mate Jenson Button also competitive during the session.
"I like the new circuit; it's got really good grip and great corners, with a lot at medium speed," he said.
"It's good fun. The car has been feeling really good today. McLaren look close which is great for everyone as it should make for a decent race. We've got quite a good balance with the car so there are a lot of boxes ticked but we still have work to do to see if we can improve for tomorrow."
Team-mate Nico Rosberg was fourth quickest and says he will revert to Hamilton's set-up after Mercedes's 'creative' approach failed to pay off.
"The team decided to go two different ways in terms of setup," he said. "I took a very creative setup for my car in the second practice session, which didn't work out. So we will go back to the conservative way for tomorrow, because we saw that Lewis was very quick with that.
"The track is really cool to drive, very enjoyable. Turn three is a very special one and the asphalt is very smooth, so the tyres last long. We won't see that many pit stops on Sunday, I guess. That's a bit surprising to me."