Nico Rosberg says he is feeling "confident" following practice on Friday for the 2015 F1 Malaysian Grand Prix, but remains concerned about reliability after team-mate Lewis Hamilton was dogged by problems.

Rosberg was quickest in opening practice at Sepang, managing a 1m 40.124s lap, that left him 0.373s up on Kimi Raikkonen.

However in the second session, he slipped back to third, ending FP2 0.428s off Hamilton, even though the Briton had missed all of FP1 and most of FP2 due to a power unit inlet system failure.

Related Articles

"We had reliability issues today with Lewis' car, but no problem on mine for now. That [Hamilton's issues] is not ideal for sure. They are going to have to find a solution overnight, but I am confident," Rosberg told reporters, including Crash.net.

"I am fine in the car and the pace is good. It seems that again Ferrari is pretty close, so we need to keep an eye on them."

Meanwhile, Rosberg said that the hot and humid conditions are tough for both the tyres and the drivers.

"We have different tyres this year and supposedly they suffer a bit less, but it doesn't seem like it at the moment," he continued. "Then again we had record track temperatures out there. It was more than 60 degrees on the asphalt and you can imagine we are actually sitting on the ground and I can feel the asphalt through the chassis and so the 60 degrees comes straight into the cockpit. It is extremely hot in the car - massively hot and not a good feeling.

"The prime is definitely going to be the race tyre and we will just have to see how far we can get with the soft tyre [on Sunday]."

Asked how crucial qualifying will be, he replied: "Yeah, for sure qualifying is going to be important, but also strategy wise there is a lot of tyre degradation out there and [as I said] it is very hot, so even in the race a lot can happen."