Max Verstappen has hinted that Red Bull experimenting was behind the gulf in pace separating the reigning F1 champion and Ferrari in French Grand Prix practice.
Carlos Sainz finished the day a tenth-of-a-second faster than team-mate Charles Leclerc, with Verstappen a further four-tenths adrift in the RB18 after struggling with understeer during his running.
The Dutch driver, addressing the lack of pace in FP2 after only being a tenth behind Leclerc's pace in the first session, said: "FP2 was a little bit more difficult for us.
"We didn't really get the balance we would have hoped for but also we were trying a few things with the car.
"We will have a look at it all for tomorrow and try to be closer than we were today.
"In the long run, it was a bit better but again, the tyres are running really hot and it is difficult to judge where you are. We still have a little bit of work to do."
Red Bull in the dark over tyre degradation
Red Bull's Austrian GP unravelled due to high tyre degradation in comparison to Ferrari.
Verstappen would have finished behind a Ferrari one-two had it not been for Sainz's power unit expiring.
With searing heat hitting the Paul Ricard Circuit this weekend and limited long-run simulations, asked as to how his degradation compared to two weeks ago, Verstappen replied: "That I don't know.
"This track is very hard on the tyres anyway so you cannot compare it to Austria.
"In general, we all needed a few more laps to have a good look at the long run."