Daniel Ricciardo believes the form sheet will change dramatically on Saturday after admitting his Red Bull lacked some pace in Friday practice for the Brazilian Grand Prix.
Ricciardo and teammate Max Verstappen finished down in fifth and sixth in FP2, over half a second off the pace set by Lewis Hamilton.
The Australian admitted he was struggling with his tyres towards the end of his long runs given the high track temperatures.
But with lower temperatures and rain expected to hit the track tomorrow, the Red Bull driver expects no repeat of the issues.
"The long run today, I didn't feel we were that strong towards the end of it but once track cools it will be completely different," said Ricciardo.
"Of course we will try to improve what we could have done today, but I think tomorrow is another story.
"I think the rain will be nice. It will be fun to change it up a bit. If it is a cooler as well tomorrow and Sunday it should be better for the tyres.
"Today the track was really hot so you could feel the tyres were having a hard time."
Ricciardo admitted he was surprised by the pace of the Williams, after Valtteri Bottas and Felipe Massa outpaced him.
"I think the pace relative to Mercedes and Ferrari is quite normal," said Ricciardo. "Williams is a surprise. It's good to have another team up there, it helps make it more competitive for Sunday if it stays like that."
Teammate Verstappen said Mercedes looked out of reach, but he believes Red Bull is its closest challenger.
"FP1 was good and in FP2 we made some changes and that was not fantastic," he said. "We managed to turn it around and in the long run it was all quite good again.
"Mercedes are too strong and we are behind them."
Additional reporting by Jonathan Noble