Red Bull and Sebastian Vettel dominated Friday practice at the Hungarian GP.
The world champion beat team-mate Mark Webber in both sessions, comfortably clear of the rest of the field.
Lotus's Romain Grosjean was third, ahead of Ferrari's Fernando Alonso and Felipe Massa, and Mercedes drivers Lewis Hamilton and Nico Rosberg.
Title contender Kimi Raikkonen of Lotus was only eighth after being held up by McLaren's Jenson Button on his fastest lap.
Button was ninth fastest, ahead of the Force Indias of Adrian Sutil and Paul Di Resta.
Vettel looked in formidable form on both one flying lap and during the longer race-simulation runs later in practice.
The German was 0.044 seconds ahead of Webber, who was 0.109secs clear of Grosjean, with Alonso only 0.009secs further back.
But during the race runs in the second half of the session Vettel's pace was some way clear of all his rivals, especially on the 'soft' tyre on which the drivers will qualify and start the race.
His average times over long runs on both the 'soft' and 'medium' tyres were at least 0.2secs quicker than anyone else and his first lap on the 'soft' tyre on his race simulation run was 0.5secs clear of his closest rival, Webber.
Vettel said: "It's the beginning of the weekend, and it's good to have a certain speed in the car, which I think we have.
"The car feels fine. But surely there's a lot of work, and still quite some room for improvement.
"It was a good day for us, I think, with quite some work in the background. It's obviously always nice when you feel in control of the car and you can do what you like to play around. I think the car suits the track."
Lotus are confident they can race Red Bull as long as the Mercedes cars do not qualify ahead of them and then hold them up in the early laps.
Mercedes appeared to be struggling, lacking the one-lap pace they usually show and struggling as usual on long runs.
Hamilton said: "It's difficult to know where we're going to be this weekend. The Ferraris are quite competitive, so are the Lotuses and then the Red Bull is absolutely ballistic. Whether we'll be able to match them I don't know."
Hamilton believes his team are struggling because Mercedes were banned from last week's Silverstone test, where the other teams were able to try out the new tyres Pirelli has introduced for this race.
"We don't seem to have the pace we had in the last race," he said, "but we'll make some changes tonight. We came into the weekend kind of on the back foot, trying to understand the tyres a bit."
Williams development driver Susie Wolff, in her role as BBC 5 live analyst, said: "Red Bull certainly look very strong and a lot of the other teams will be scratching their heads this evening.
"The Ferrari is better over one lap than it has been in recent races, which is what they need because their race form has been good.
"Mercedes seem to have slipped back a bit, but I think you can expect a battle at the front between Red Bull, Lotus, Ferrari and Mercedes."