Sebastian Vettel and Mark Webber dished out a stern warning to their rivals here yesterday, beneath the floodlights of Singapore's Marina Bay Circuit.
The other teams had arrived hoping that a recent tightening of the rules governing the flexibility of front wings would clip Red Bull's speed, but Vettel was 0.627sec ahead of his team-mate, and a whole second faster than third-placed Jenson Button in his updated McLaren.
Lewis Hamilton, fifth fastest behind Fernando Alonso who slid up an escape road and was unable to restart his Ferrari after it stalled when he selected reverse gear, was optimistic despite the deficit.
"The track was very tricky today because there were wet patches in some areas, but it was quite a good session for us," said Hamilton. "We're reasonably close; we're competitive; there's more time for us to find tomorrow; so I'm optimistic.
"In fact I think we'll be able to compete with the guys who were at the front today. The Red Bulls definitely aren't unbeatable here. OK, they're very quick in the second and third sectors, so we'll have to work hard to try to make up time there, but I'm pretty confident we can do it."
But Hamilton was critical of revisions to the chicane, and said: "I think they have made it worse; the chicane is now very tricky. You approach it at 170mph, and if something goes wrong, and you hit one of those curbs, you could have a nasty accident."
Meanwhile Michael Schumacher, 10th fastest, did his best to scotch rumours that he won't be driving for Mercedes next year, as other sources suggest he will assume a joint team-principal role with his long-time ally Ross Brawn and that Force India's Adrian Sutil will partner Nico Rosberg in the cockpits.
"You cannot get rid of me, let's put it this way," Schumacher said of the rumours. "Our goal is naturally to win the championship, better earlier than later. But it is a process and we are not magic, so we are trying to maximise our opportunity in deciding early to prepare for 2011.
"In my first activity with Benetton it took me about four years to finally win a championship, in Ferrari it took me five years and I hope we are much more efficient here."