Ferrari must resolve their baffling loss of pace before Felipe Massa fights Lewis Hamilton for the Formula One title in Brazil next week, team boss Stefano Domenicali has said.
McLaren's Hamilton took a pole to flag victory in China on Sunday to extend his championship lead over Massa to seven points.
The Briton now needs only to finish in the top five in the final race in Brazil on November. 2 to become Formula One's youngest champion at 23.
Brazilian Massa finished second in China, after being let past by team mate Kimi Raikkonen, but never threatened Hamilton during the race.
''The thing that we need to understand, going to Brazil, is why and how this was possible considering that in Singapore and in Fuji (at the Japanese Grand Prix) we were really fast, both in terms of quick laps and race pace,'' Domenicali told Ferrari's website today.
''This race (in Shanghai) was the worst, from the performance side, that we have had this year in these conditions, together with Germany.'' Brazil's Massa finished third at Hockenheim in July with tyres partly blamed for that performance, but Domenicali said the handling of the car was as much at fault this time.
''We need to understand why there was this kind of change on the performance side,'' he said. ''We need to make a careful analysis to understand exactly the reason why we lost performance.'' The Ferrari boss praised Hamilton for his victory.
''Lewis was in another league, he was driving perfectly, fast, consistent and we couldn't even think of attacking him,'' he said.
The Briton led the championship heading into Brazil last season but threw away his chance, with Raikkonen grabbing the title by a point after also being seven adrift before the final race.
Domenicali, whose team lead McLaren in the constructors' standings by 11 points, said both were wary of the unexpected in Massa's home race at Interlagos.
''We know that everyone is concentrated but terrified that something unexpected can happen,'' he said.
''For sure, I'm expecting Lewis to think 'Oh my God, I'm not expecting to have another difficult race'. On the other hand you may think Felipe is doing the same, and we are doing the same as a team.''