Valtteri Bottas has admitted that he is "positively surprised" after his first experience of the Russian Grand Prix circuit in Sochi.

The F1 grid took to the streets of the Black Sea resort for first and second practice on Friday, with Mercedes' Lewis Hamilton comfortably finishing top of the timesheets in the afternoon.

For Bottas, fifth place in FP2 was a good result, but the Finn admitted that there are still obstacles to overcome regarding tyre wear.

He told reporters: "I'm positively surprised by the track as it's more challenging than I expected with quite a few technical sections, especially the final sector and I found it enjoyable to drive.

"The asphalt is quite smooth and combined with the hard compounds we saw little tyre degradation today, but this has corresponding challenges as it makes it harder to get the tyres to work on your opening laps.

"We therefore have work to do to make sure we get the most out of the tyres for qualifying tomorrow but overall a good start for us and this track seems to suit our car pretty well."

Bottas is currently sixth in the drivers' standings, three points behind Ferrari's Fernando Alonso.