By Alan Baldwin
AUSTIN, Texas (Reuters) - Formula One teams usually bring upgrades to races but Ferrari opted for a 'downgrade' at the U.S. Grand Prix and it turned out to be a winner.
Title contender Sebastian Vettel, whose veteran team mate Kimi Raikkonen won Sunday's race, told reporters that the team had gone back to what had worked before by removing some recent 'improvements'.
"It took too long," the German said about the car's recovered performance.
"You can see it as good news but you can also see it as bad news. If we have to go back to a car that has been competitive three or four months ago, then surely it can’t be good news. If you think about it."
Raikkonen's win was Ferrari's first since Vettel triumphed in Belgium at the end of August.
Since then, Mercedes' championship leader Lewis Hamilton had won four races in a row.
Vettel, now 70 points behind Hamilton with three races remaining, said it was hard to explain what had gone wrong since Spa-Francorchamps.
"Certainly we felt that the car was not as strong as it was before, but if you don’t see there is anything wrong then you don’t know there is something wrong," he added.
"I think all the steps we did, they seemed to make sense but obviously now looking back they didn’t.
"Clearly there was something we missed and we haven’t yet understood why and where the error took off or started. So there's a lot of stuff for us to do. But I’m pretty sure we will do what is necessary and get on top of it."
Raikkonen's win was the 39-year-old Finn's first since 2013, a record gap of 113 races between victories.
It may also prove to have been his last, with the 2007 world champion leaving Ferrari for Sauber at the end of the year and Monaco's Charles Leclerc going in the other direction.
Vettel said there would be plenty of homework for the team to do over the European winter.
"I have no problem admitting the mistakes that I have done. On top I think there were some things that happened to us that didn’t help us," he said.
"But yes, I think the crucial bit has been that for a big part of the season we didn’t have the speed to really be there and then other stuff happened. I think overall we have the potential, I think we need to still grow and learn.
"So there will be a lot of stuff over the winter that we need to review, all of us including myself."
(Reporting by Alan Baldwin, editing by Pritha Sarkar)