Kimi Raikkonen said Ferrari had a "tricky day" in Shanghai on Friday despite topping the afternoon practice session.
Raikkonen led a Ferrari one-two in FP2, with Mercedes 0.237s adrift on the super-soft tyre. Though he topped the session Raikkonen admits the team is still trying to get to grips with the medium and soft compounds.
"It's been quite a tricky day," Raikkonen said. "I don't know if it's the conditions or the wind or something but I was sliding a lot and obviously not feeling very nice. Once we put the supers-oft tyres on we have more grip from the tyres and that helps.
"For whatever reason we've been quite struggling apart from the super-soft tyre. Our car is nice but it's just the other tyres are very difficult to get any grip from. But I had a pretty OK lap and the long run on the super-soft was OK."
Mercedes tends to hold back its quickest engine modes for qualifying and also set its laps earlier in the session when the track had less grip. However, Ferrari' will be buoyed by its pace on Friday afternoon but Raikkonen is refusing to make any bold predictions.
Asked if Ferrari can take pole in China, Raikkonen replied: "I don't know, we'll see how the weather turns out to be tomorrow and we'll try to make the maximum out of the race and see how we do."