Jenson Button says he is unsure about the newly resurfaced Sepang circuit, which he described as "very strange" following first and second practice on Friday.
The McLaren driver finished tenth in both sessions, but believes there is more to come from the car after team-mate Fernando Alonso – who is running an upgraded engine – was sixth quickest.
"We were out a bit late in FP2 because some of the set-up changes we made to the car took a little bit longer than we thought. That meant I got out when everybody else was on high-fuel. Then I caught up with Kevin [Magnussen] in Turn 10, and he kept on the racing line, which hurt me in terms of lap-time," he said.
"So the single-lap pace of the car isn’t too bad – and I even think we can be further up tomorrow. The long-run pace isn’t quite there yet – but we think we know what we can do with the balance to help that."
When asked about the track itself, he added: "The new asphalt here is very strange – it feels like there’s a lot of grip, then it’s suddenly taken away from you. It’s difficult to read – it feels a bit like Sochi: the oversteer comes out of nowhere."
Meanwhile Alonso was positive about the changes which he says have added "lots of grip".
"The new asphalt is a good improvement: there’s a lot more grip. Last year, my best Friday time was a 1m42.5s; this year I set 1.36.2 – so that’s six seconds in one year. If you consider the car has improved by two- to two-and-a-half-seconds, we get a further three seconds from the asphalt. It’s a good sensation to have so much grip."
