Sergio Perez has hinted at an issue with Red Bull's simulator correlation after claiming the RB18 was "miles off" compared to his preparation work for the British Grand Prix.
The Mexican finished second practice eight-tenths of a second adrift of Ferrari's Carlos Sainz in seventh, with Mercedes' Lewis Hamilton, McLaren's Lando Norris and Alpine's Fernando Alonso also finding greater pace.
Team-mate Max Verstappen finished only fourth with Ferrari seemingly stronger in both high and low fuel runs.
"It wasn't a great session," conceded Perez. "From the preparation we had in the simulator, the car was miles off so we assume there is something going on that we need to understand.
"It was a very short long run at the end. Not a great start, we are bit on the back foot so we just need to understand what is going on with it."
Perez hoping to rediscover confidence
Perez had been enjoying a purple patch of form before the Canadian Grand Prix last time out, where a qualifying crash and a reliability issue in the race set him back.
The apparent correlation issues at Silverstone have left Perez short on confidence, with Red Bull placed further on the back foot by the lack of running during a wet FP1.
"It is going to be pretty difficult [to come back] but we have done it before and as long as we are able to get the things in the right place, you need confidence around these fast corners," said Perez.
"So as long as I am able to get my confidence back, things should be alright."