Fernando Alonso warned that Ferrari will be less competitive in the Singapore Grand Prix than it was at Monza two weeks ago after two difficult Friday practice sessions.
Ferrari's new rear wing design appeared not to work as hoped, leading to a switch back to the "baseline" wing, and although Alonso was third quickest, he said it was clear that the twisty, low-grip Marina Bay street circuit was a tough venue for his car.
"We tried various new components on the car: some seem to be positive, others less so, but maybe in the case of the latter, we need to spend a bit more time for them to be developed as well as possible," he said. "Overall, I would say today was positive, even if the first impression is that we are not as competitive as we were in Monza, two weeks ago.
"We still lack a bit of performance on tracks like this one, where you need maximum aerodynamic downforce."
His teammate Felipe Massa was ninth quickest. While Alonso had concentrated mainly on Ferrari's upgrades, the Brazilian had worked on the car's balance, and was not satisfied.
"It wasn't an easy day for me," he said. "The car wasn't right all day and I also suffered particularly badly with tire degradation in both sessions.
"At the end of the second session, we found something that wasn't working properly, but that doesn't explain all my problems. We must find out what happened so we can fix it for the rest of the weekend. We have reasonably clear ideas about the direction to go in when it comes to setup. One thing's certain, there's a lot of work to do."