Nico Rosberg fears that Mercedes will have more issues with their tyres at the Chinese Grand Prix this weekend.
Practice is now underway for the race, which takes place on Sunday at the Shanghai International Circuit.
And despite strong performance in qualifying for previous rounds, Mercedes have been slow to get off the grid, due in part to problems acclimatizing to the new Pirelli tyres.
Rosberg and team-mate Michael Schumacher have just one point between them at present.
Ahead of the race, the young German was quoted by Autosport saying: "The big problem is with the tyres on this track, especially the front tyres, they destroy very easily so you have to be very careful and find a set-up for the car to help that."
Schumacher managed to post the fastest time in the second practice session today, but Rosberg remains cautious about the Mercedes car in actual race conditions.
"It is not so easy because in the race we are still having some difficulties, in qualifying we are very good and we will try very hard to improve but it will take some time."