Sebastian Vettel headed team-mate Mark Webber as Red Bull took a dominant one-two in Friday practice at the Indian Grand Prix.
Vettel, on the verge of a fourth title after winning the last five races, was nearly 0.5 seconds quicker than Lotus driver Romain Grosjean in third.
Mercedes drivers Lewis Hamilton and Nico Rosberg were fourth and sixth, sandwiching Ferrari's Fernando Alonso.
McLaren's Sergio Perez and Jenson Button rounded out the top 10.
Vettel appears to be in control at the Buddh International Circuit, setting the fastest time in the low-fuel, qualifying trim and also on the medium tyres, which will be the preferred choice in the race, when running a heavier fuel load later in the session.
On pure pace, the German ended the session 0.289secs clear of Webber, 0.498secs ahead of Grosjean and 0.677secs clear of Hamilton, who was 0.031secs ahead of Alonso.
Red Bull team principal Christian Horner said: "We worked through a programme and had a good look at the tyres, which seemed to be fairly contrasting.
"You couldn't have two more diametrically opposed tyres - one that lasts forever, the other that lasts not very long at all - but it was a positive day."
He added that Lotus and Ferrari "have looked pretty strong" and thought Mercedes would be competitive, too.
Red Bull driver Mark Webber said: "We're going OK on both short and longish runs. We have to look through everything tonight. We have some work to do."
However, the Red Bull appeared to wear the 'soft' tyres very rapidly on race fuel levels. These will be the tyres the leading drivers have to start the race on after setting their qualifying times on them.
Vettel managed only three laps of his race-simulation run on that tyre before they were effectively destroyed, whereas Alonso managed 10.
"The soft tyre is not lasting very long but it's Friday," said Vettel. "The track is rubbering in and it improves usually for Saturday, plus we haven't used this compound for a long time so I think tomorrow we should be in a better place."
But Hamilton said he felt fighting for pole position would be impossible.
And Rosberg added: We're fighting for third place on the podium because the Red Bulls are just too quick again. Pole is also out of the question because they are too fast - especially Vettel. It's a bit of a pity, but that's just the way it is."
BBC F1 technical analyst Gary Anderson does not think Vettel, who was won both Indian races run so far, is guaranteed victory on Sunday.
"I don't think it's all over," he said. "I think it will be harder for Vettel than the last two years. Mercedes and Lotus look quite close."
Lotus reserve driver Davide Valsecchi, acting as BBC 5 live analyst, said: "It was an interesting day. It seems like Red Bull will be really difficult to beat.
"The only team that seems to drop in performance is Sauber. They were sixth and seventh on the grid in Suzuka [two weeks ago] but here they are outside the top 10."
Sauber's fastest driver was Nico Hulkenberg in 14th place, behind Toro Rosso's Daniel Ricciardo in 11th, Force India's Adrian Sutil in 12th and the Williams of Valtteri Bottas in 13th.