Red Bull's Sebastian Vettel headed McLaren's Lewis Hamilton in Abu Dhabi Grand Prix second practice.
The world championship leader was 0.168 seconds quicker than Hamilton,
who set the pace in the first session.
McLaren's Jenson Button was third fastest ahead of Red Bull's Mark Webber, with Vettel's title rival Fernando Alonso of Ferrari only seventh.
Lotus drivers Romain Grosjean and Kimi Raikkonen were fifth and sixth.
Abu Dhabi second practice top 10
1 Sebastian Vettel - Red Bull 1:41.751
2 Lewis Hamilton - McLaren 1:41.919 +0.168
3 Jenson Button - McLaren 1:42.412 +0.661
4 Mark Webber - Red Bull 1:42.466 +0.715
5 Romain Grosjean - Lotus 1:42.500 +0.749
6 Kimi Raikkonen - Lotus 1:42.532 +0.781
7 Fernando Alonso - Ferrari 1:42.587 +0.836
8 Felipe Massa - Ferrari 1:42.823 +1.072
9 Pastor Maldonado - Williams 1:42.998 +1.247
10 Sergio Perez - Sauber 1:43.106 +1.355
The headline lap times look discouraging for Ferrari, who have a series of new parts in Abu Dhabi in an attempt to close the performance gap between themselves and Red Bull.
A major development to the Red Bull
car starting at the Singapore Grand Prix at the end of September and refined ever since has moved Vettel's team onto a separate level from their opposition and Ferrari have been unable to respond.
The result has been that Vettel has won four consecutive races and
moved into a 13-point lead in the championship
with 75 still available in the remaining three races, including this weekend's in Abu Dhabi.
Ferrari have taken a new front wing, new under-nose barge boards and new rear wing endplates to Abu Dhabi.
Alonso spent the two sessions assessing the new parts and ended up with all of them on the car, suggesting Ferrari were pleased they were an improvement, but never looked to be anywhere near the pace of the Red Bulls or McLarens.
BBC F1 technical analyst Gary Anderson said the new front wing was aimed at improving consistency of downforce, while the new rear wing was aimed at working in conjunction with a new diffuser introduced at the last race in India.
BBC F1 technical analyst
“If you can get all that to connect up, it can give you 0.2secs quite quickly - which would put them much closer to Red Bull in qualifying”
"If you can get all that to connect up, it can give you 0.2secs quite quickly - which would put them much closer to Red Bull in qualifying," Anderson said. "But it's like a light switch, not a dimmer switch. It either works or it doesn't, and we don't know yet whether it has."
Alonso did set the fastest outright lap time during the race-simulation runs later in the session, but it is impossible to know whether the cars were in the same specification as each other.
Ferrari technical director Pat Fry said: "We are pushing as hard as we can to bring updates to every race. Some of the ones we introduced here seem to be positive, but we must carefully evaluate their performance and then decide which to use in qualifying and the race.
"Felipe's long run didn't seem too bad, but clearly we have to improve our performance over a single lap if we want to start from the front row of the grid."
On race-simulation times, McLaren appeared to have a slight advantage over Vettel and the German's comments after the session confirmed that.
"We got a very good lap in on soft tyres," said Vettel. "But in terms of general pace the McLarens were on top of us and they seem very competitive so they are the ones we need to look out for and we need to beat.
"We are not entirely happy with the car, we can improve it and we must do that tomorrow to make sure we qualify as high up as we can.
"Lewis was very quick on the medium tyre so we have to do a little bit of catching up to ensure we are close to them and possibly ahead tomorrow."
Lewis Hamilton ran into problems with his steering, saying there was a "dead band in the middle of the steering rack" but that it would be changed for Saturday's sessions.
"It's been an interesting day," said Hamilton. "We have got through quite a lot. It seemed quite good in P1. P2 was a bit of a struggle for me. I set a good time on the prime but people found about 0.8secs on the option and I wasn't able to get any time out of it. Perhaps it's about switching the tyres on."
"The car is in a better place than it was in India," said Button. "On low fuel it seems to take a lot of laps to get the lap time out of it. I only did three laps on the 'option' so I probably didn't get the best out of the tyre but I wanted to get onto the long run."
Webber missed the end of the session with a mechanical problem that kept him consigned to the garage.
"Looks like the water generator or some Kers issue," he said. "Not great. But that was today and come back tomorrow. It's never a help to have less running."
Abu Dhabi Grand Prix 2012, day two
- Saturday, 3 November: Third practice 09:55 GMT; 5 live sports extra, red button and online. Qualifying 13:00; BBC One (from 12:10), online and 5 live sports extra (from 12:55).
Abu Dhabi Grand Prix 2012, day three
- Sunday, 4 November: Race 13:00; BBC One (from 12:10), online and Radio 5 live (from 12:55); Race highlights 19:00 BBC Three.