Sergio Perez says Red Bull is "too far away" from Ferrari after the opening day of practice at the Singapore Grand Prix.
Perez and team-mate Max Verstappen struggled during the first two practice outings, with Perez exclaiming over team radio that he felt like he was going to crash at every braking zone due to a lack of balance and grip from his RB19.
Red Bull has enjoyed a dominant season thus far, winning all 14 races staged.
However, the ended the second practice session at the Marina Bay Circuit in seventh and eighth, with Perez leading the World Champion.
"There are so many interesting bits going on that we need to figure it out overnight, hopefully," Perez told F1TV.
"We seem to be struggling quite a bit with the rear end of the car, especially in FP2.
"There’s] plenty of things to look at and hopefully we can come up with the best possible set up because we know that qualifying is very, very important.”
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Perez admits surprise over Ferrari
While Red Bull struggled around the track, Ferrari excelled and topped both practice sessions.
The Italian squad was two-tenths of a second ahead of the competition at the end of FP2, with Perez admitting surprise over its advantage.
"We didn't expect Ferrari to be very strong around here," the Mexican stated.
"I mean, we’re just too far away. Hopefully tomorrow we will be able to close the gap a bit more. But I do expect quite a challenge.”
Traffic was also an issue for some drivers during Friday practice, but Perez highlighted that Red Bull has bigger issues to worry about.
"I think in Q3 it should be all very straightforward," he said. "I don't think we are relying anything on that."
"The main thing is to make sure we are able to improve the balance [of the car] as at the moment, we are far off."