Fernando Alonso believes Ferrari's inability to adapt to the changes that Pirelli made to their tyres cost them dearly in the title race.
With two victories and three further podiums to his name during the opening eight grands prix of the season, Alonso appeared to be on course to challenge Sebastian Vettel for the World Championship.
However, Pirelli were forced to make changes to the structure of their tyres after several drivers suffered blowouts at the British Grand Prix.
While other teams were quick to upgrade their cars to adapt to the changes, Ferrari couldn't quite match their rivals and Alonso quickly fell behind in the race for the 2013 Championship.
Although the Spaniard concedes Pirelli had to make the changes, he believes the Scuderia lost out because they couldn't keep up when it came to developing their car in line with the tyre tweaks.
"I think the problem was our development," he is quoted as saying by Autosport. "We didn't adapt to the tyre, or didn't have the steps that we planned.
"We arrived especially in July to the races with some good updates on paper, but not so much on the track. I think that slowed down the performance improvements that we should have had.
"The Pirelli [change] is an extra. It is clear that there are some teams that lost a little bit of performance, and some teams that win a little bit of performance like Sauber. But they [Pirelli] had to make the changes because the tyres explode.
"So it was not a decision to make better one team or another team. It was a change to continue racing in the Championship. So there was nothing we can do."