Felipe Massa is concerned that he is no longer able to find the balance he needs with his Ferrari to be on the pace after he could only qualify ninth for this weekend's Spanish Grand Prix.
The Brazilian was unable to match his team-mate Fernando Alonso, who will start from the second row, and he admitted on Saturday evening that he was still unsure of what was causing his problems.
"Fernando is a very good driver, but something has happened to me," said Massa. "Something is not going like I want, so I can't do the lap time or drive the car like I want.
"This is something that we need to understand, and improve. It will be difficult for tomorrow because we cannot change the car, but we need to do something for the next races.
Massa added that he had been happier with his car in practice, but could not repeat his performance in qualifying.
"I was struggling a lot to find the right balance in the car. This morning my feeling was a bit better, and then in qualifying I was slower on the hard tyre than I was in practice," he said.
"We need to understand what has happened, understand which direction to follow. I went in a completely different direction [to Alonso], and then back again. We tried everything.
"It looks like something is not working out to give the grip. This is something that we need to understand, but I'm sure we will."