(CNN) -- Red Bull proved they will be the team to beat at this weekend's Singapore Grand Prix after dominating Friday's two practice sessions.
Drivers' championship leader Mark Webber posted the fastest lap in a rain-hit morning session, and came second to teammate Sebastian Vettel in the afternoon.
McLaren's Jenson Button was third in the second session while teammate Lewis Hamilton was fifth. The pair sandwiched Ferrari's Fernando Alonso, who was fourth.
It means the five drivers at the top of the world championship standings posted the five quickest times in more favorable racing conditions later in the day.
The opening session was severely hampered by poor weather allowing seven-time world champion Michael Schumacher, of Mercedes GP, to finish narrowly behind Webber's time of one minute 54.589 seconds.
But as the track dried up for the second session the leaderboard had a distinctive feel to it as this season's title contenders upped the pace.
Vettel's time of one minute 46.660 seconds was well ahead of Webber, who posted one minute 47.827. Button was third while Alonso hung on to fourth after going off the track during his fastest lap.
After the session Vettel told the official Formula One website: "The most important thing is to have a clean Friday and we had no problem with the car today. I think it could be interesting Saturday or on Sunday if we get some rain.
"It doesn't mean so much to be P1 today, as it's only practice and there are no points available, but it's still good to be on top and we have good pace. The weather may bring a surprise though."
Webber said: "A pretty good first day, the first session was wet, but we got some good running this afternoon. I haven't seen the times that closely yet, but I'm pretty happy with how today went.
"I need to work on my short run performance a bit, but overall it's good. Other people had their ideas how to improve their car and we have continued to improve our car too.
"Ferrari still look quick and anyone can be on pole tomorrow, us, Ferrari or McLaren, we just keep trying to do our best."
Lewis Hamilton was over a second behind Vettel but insisted McLaren could pick up pace during Saturday's practice session ahead of qualifying.
He told McLaren's website: "The track was very tricky today because there were wet patches in some areas, but it was quite a good session for us. We're reasonably close; we're competitive; there's more time for us to find Saturday; 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. Okay, 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."
Jensen Button said: "We got some reasonable running during P2, and the car is working quite well. There are still some improvements we need to make, but I feel comfortable with it."