Ferrari's Sebastian Vettel was fastest in second practice at the Hungarian Grand Prix while his title rival Lewis Hamilton was only fifth for Mercedes.
Hamilton and team-mate Valtteri Bottas made errors on their fastest laps in a car that appeared to lack rear grip.
Max Verstappen's Red Bull was 0.074secs down on Vettel, with their respective team-mates Daniel Ricciardo and Kimi Raikkonen a couple of tenths back.
Hamilton ended up an unrepresentative 0.753secs off the pace.
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Had the Mercedes drivers completed their laps, it appeared as if Hamilton could have been around third place on a track where the team were expecting to struggle a little compared to Ferrari.
"It has been a relatively normal day," said Hamilton. "As we expected, the Ferraris and the Red Bulls were quite quick and had a little bit more pace than us, so we've got some work to do tonight.
"This is a tricky circuit and the tyres are overheating; looking after the rear tyres is the biggest issue. The temperatures today and the layout of the track - corner after corner after corner - made it really tricky for the tyres as there's no time for them to cool down."
Hamilton is 17 points clear of Vettel following his victory in Sunday's German Grand Prix, where the Ferrari driver crashed out of the lead and Hamilton came from 14th on the grid to win.
Ferrari appear to have the expected edge over Mercedes on the tight and twisty Hungaroring, looking quicker in both qualifying pace and race pace.
"The qualifying and the start is very important, overtaking is very difficult - if we are ahead after the first corners that will be crucial. The car is pretty good for one lap, we can still improve but it has been one of the better Fridays," said Vettel.
Asked about his German Grand Prix disappointment, he said: "It is good to have a race straight away to get your head away and hopefully we can cancel it out and make this race count and forget properly."
Red Bull look quick on long runs, but the question is whether they can compete for the front row in qualifying when Mercedes and Ferrari turn up their engines into an extra power mode that Renault do not have.
Romain Grosjean was best of the rest for Haas, ahead of the Renault of Carlos Sainz, Pierre Gasly's Toro Rosso, the Force Indias of Esteban Ocon and Sergio Perez and Fernando Alonso's McLaren.
Kavin Magnussen's Haas was 13th after missing his qualifying run because of engine problems, while Renault's Nico Hulkenberg was 14th, starting the session later because of an energy-store change after a failure in the first session.
Alonso's team-mate Stoffel Vandoorne was 19th after spinning into Turn Five on his qualifying simulation run when he put his left rear wheel on the grass on entry.
Sauber's Marcus Ericsson made it three spins in one day with an off at the final corner but, in 16th place, he still managed to edge out team-mate Charles Leclerc, who missed the first session because Ferrari third driver Antonio Giovinazzi was driving his car.