Russian GP: F1 drivers praise Sochi circuit after practice

Mercedes set the pace in both sessions on the new 3.6-mile circuit, based on the site of the Olympic park, and championship leader Lewis Hamilton said he had "really enjoyed" his first experience of the track.

"It's got a really nice flow to it, it's not too bumpy, the corners are challenging - if you can get the lines just perfect you can put together really nice sectors," he said.

"The tyres are also not falling apart, which they do at other tracks, so it's even more fun because you can do lap after lap and enjoy it."

Red Bull's Daniel Ricciardo said the circuit had proved more challenging to drive than expected.

"It is more technical and difficult than it looked on paper," he said.

"It seemed quite hard to get the lap together and has quite a few off camber corners, which isn't always fun for a driver, but it does make it challenging and I think a lot more mistakes were made.

"The actual circuit is alright. We are not particularly quick at the moment, so you never love a circuit if you are not fast.

"Turn 13 is really quick. You open the DRS, and just before you brake the car gets a bit light.

"Some people are opting to take the DRS off a little bit early to get some more stability on braking. It is tricky, but it is quite fun [and] quite a good challenge."

McLaren's Jenson Button reckoned the reality of the circuit was a significant improvement on team simulations.

"In the simulator it wasn't fun to drive at all, but it's nice to drive," Button said.

"I'm happy with the job they've done. There are a few places that are quite bumpy, but that just adds to the circuit."

Lotus driver Romain Grosjean reckoned overtaking would be difficult in the race, despite the circuit having one of the longest straights on the calendar.

"It's going to be quite tough to overtake, unless the DRS is powerful, because under braking itself it's difficult," he said.

"It [the start/finish straight] is quite long, but the DRS opens quite late - in the middle of Turn 1 - and then if you close the door the braking is going to be difficult; you cannot go to the outside because the other guy will push you wide."