Mercedes driver Lewis Hamilton says he is expecting a close battle with rivals during this weekend's Singapore Grand Prix.
Hamilton was fourth fastest in the second practice session, which was topped by Red Bull driver Daniil Kvyat.
Hamilton also trailed Ferrari's Kimi Raikkonen and the other Red Bull of Daniel Ricciardo.
"The sessions were good, we got on with our programme," he said.
"It was very enjoyable and the track is very physical. The car feels good but the others are much closer this weekend.
"It's always the case here. There are no problems with the car but everyone looks closer, if not a bit faster.
"We'll still be fighting, we just need to work hard and find out where the time is. Qualifying is very important as overtaking looks very difficult so we'll see what tomorrow brings."
Team-mate Nico Rosberg was seventh fastest during the second session.
"In the first practice session I felt good in the car; I did some changes with the setup between the sessions, but I went in the wrong direction," he said.
"It was good experience, as I know now what to do for tomorrow. The track is very demanding and tyre wear seems to be very high."