Carlos Sainz and Charles Leclerc topped FP1 and FP2 respectively at the Hungarian Grand Prix, with Leclerc leading the latter session ahead of McLaren's Lando Norris and Sainz.
World championship leader Verstappen placed fourth just under three tenths behind Leclerc and fears his Red Bull team won't be able to keep up if it stays dry in Budapest.
Fortunately for Verstappen, heavy rain is expected, giving the Dutchman some hope that Red Bull can be in the fight.
"I think they are a bit ahead of us and I think it will be hard for us to beat that," Verstappen said on Friday evening.
"Overnight we'll try to close the gap as much as you can and see what the weather will give us as well tomorrow.
"I think in the dry we can't compete so maybe in the rain we can, who knows."
Verstappen said Red Bull still had some homework to do after struggling to find the optimal balance on the twisty and demanding Hungaroring.
"A bit tricky as expected around here, just trying to find a bit of a balance from high to low speed," he said.
"Sometimes it works a bit better, sometimes a bit more tricky. But yeah, bit of work to do."
Team-mate Sergio Perez was upbeat despite finishing the day down in ninth, nearly a second away from Leclerc, having been experimenting with the set-up of his RB18.
"I think it was a day of trying very different bits to definitely get comfortable with the car," Perez explained.
"I think we got a good idea, good understanding of the day, so hopefully tomorrow we can be able to show what we've learned today and that should also transform into the high fuel and low fuel pace.
"I'm fairly optimistic but yeah, certainly the Ferrari looked very strong today. They are definitely very, very fast.
"Hopefully tomorrow with a bit of rain things can become a bit more mixed. It should mix things up fairly nicely, so looking forward to it."
