Ferrari says it has seen encouraging signs of progress from Pirelli during this week's Formula 1 tyre test in Bahrain.
Although the three-day run at Sakhir was marred by a 200mph tyre blowout for Nico Rosberg that ended Mercedes' testing early, Ferrari team principal Stefano Domenicali has revealed that there have also been some positive indications.
In particular, he says that the running there has shown that the problems of marbles, which drivers have complained about, appears to have been solved.
"Pirelli has been working in Bahrain, which is one of the most difficult tracks we go to. That is why it was important we are going to test there in February," he said.
"Next year's tyres are not going to be defined after this test, but after the second session in Bahrain, and we are adapting to the new tyres.
"But we have seen so far that even though only four cars have been running that the marbles seem to be improved."
Ferrari development driver Pedro de la Rosa and its protege and Marussia race driver Jules Bianchi have carried out driving duties for the Italian squad at the test.
Domenicali commended Pirelli's efforts to make improvements for 2014.
"Pirelli is working hard to respond to a difficult season and a difficult situation it has faced," he said.