Vettel keeps RBR on top in Singapore

Once up to speed, Vettel dominated much of the session, putting in a 1m48.559s to go fastest ahead of early pace-setter Fernando Alonso after 25 minutes.

McLaren's Jenson Button deposed Vettel with a run on the softer tyres just after the halfway point - but when the German changed to super softs not only did he go quickest, but went on to repeatedly extend his advantage with a blistering run that took him a second clear of the field.

That margin initially remained even when Webber brought the second Red Bull up to second, though the Australian later closed to within 0.627s.

Alonso was the only man who looked capable of threatening Vettel. The Ferrari driver beat the Red Bull's first sector time and was quick in sector two as well, but then had a lurid moment on the Turn 17 kerb before sliding down the escape road at the next corner. Alonso reversed back out, only to stall when he reached the racetrack and have to abandon his Ferrari, ending his session 20 minutes early.

The other driver to make a significant mistake was Adrian Sutil, who took a violent ride over the Turn 10 chicane kerbs. The Force India took to the air and landed heavily on the next kerb, smashing its left front suspension.

Despite his excursion, Alonso's time still kept him fourth, between the two McLaren drivers, with Button remaining third and Lewis Hamilton taking fifth, as the five title contenders led the way.

Rubens Barrichello was best of the rest, taking an encouraging sixth for Williams ahead of Felipe Massa in the second Ferrari.

Mercedes was eighth and 10th with Nico Rosberg and Michael Schumacher, split by Robert Kubica - who spent a lot of the session in the Renault garage while his car received attention.

Nick Heidfeld was again right behind his Sauber team-mate Kamui Kobayashi as the duo took 12th and 13th. Fellow returnee Christian Klien was slowest of all - with Hispania a second adrift of its nearest rivals and 8s off the overall pace.

Pos  Driver         Team                    Time              Laps
 1.  Vettel         Red Bull-Renault        1:46.660            29
 2.  Webber         Red Bull-Renault        1:47.287  + 0.627   27
 3.  Button         McLaren-Mercedes        1:47.690  + 1.030   28
 4.  Alonso         Ferrari                 1:47.718  + 1.058   20
 5.  Hamilton       McLaren-Mercedes        1:47.818  + 1.158   28
 6.  Barrichello    Williams-Cosworth       1:48.302  + 1.642   31
 7.  Massa          Ferrari                 1:48.341  + 1.681   28
 8.  Rosberg        Mercedes                1:48.679  + 2.019   26
 9.  Kubica         Renault                 1:48.855  + 2.195   15
10.  Schumacher     Mercedes                1:48.889  + 2.229   31
11.  Hulkenberg     Williams-Cosworth       1:49.153  + 2.493   32
12.  Kobayashi      Sauber-Ferrari          1:49.438  + 2.778   30
13.  Heidfeld       Sauber-Ferrari          1:49.558  + 2.898   26
14.  Petrov         Renault                 1:49.608  + 2.948   30
15.  Liuzzi         Force India-Mercedes    1:49.896  + 3.236   28
16.  Sutil          Force India-Mercedes    1:49.984  + 3.324   11
17.  Alguersuari    Toro Rosso-Ferrari      1:50.191  + 3.531   31
18.  Buemi          Toro Rosso-Ferrari      1:50.896  + 4.236   35
19.  Kovalainen     Lotus-Cosworth          1:51.878  + 5.218   30
20.  Glock          Virgin-Cosworth         1:52.150  + 5.490   22
21.  di Grassi      Virgin-Cosworth         1:53.431  + 6.771   25
22.  Trulli         Lotus-Cosworth          1:53.526  + 6.866   27
23.  Senna          HRT-Cosworth            1:54.725  + 8.065   27
24.  Klien          HRT-Cosworth            1:55.542  + 8.882   25

All Timing Unofficial