Red Bull had serious concerns about tyres before finishing first and second in the Belgian grand prix.
That is the claim of team boss Christian Horner, who asked the FIA for permission prior to the Spa-Francorchamps race for Sebastian Vettel and Mark Webber to be allowed to change their qualifying tyres due to blistering damage.
"It is a fantastic result but we had to be quite conservative," Briton Horner told German RTL television in Belgium.
"We even thought about starting with hard tyres from the pitlane. It wouldn't have been good for the championship but the risk was quite big.
"The blisters were clearly visible," Horner continued, "not only on our cars but also all of the fast cars seemed to have problems as well."
We even thought about starting with hard tyres from the pitlane
Vettel, returning to the top step of the podium on Sunday after failing to win a single race in July, seems now to be cruising to his second world title.
But Horner admitted that Monza in two weeks will be Red Bull's "biggest challenge of this year" due to its high speed straights.
"We will have a big fight on our hands," he said.