Jenson Button tops opening Abu Dhabi Grand Prix practice

The Woking squad was denied a one-two in the final moments though, when Lewis Hamilton was bumped down to third by Red Bull's Mark Webber. World champion Sebastian Vettel was fourth fastest ahead of Fernando Alonso and Felipe Massa - despite a problematic session for Ferrari.

Adrian Sutil set an impressive seventh fastest time for Force India late on, bumping Mercedes driver Nico Rosberg to eighth. Paul di Resta and Jaime Alguersuari completed the top ten, while Friday testers Jean-Eric Vergne (Toro Rosso) and Romain Grosjean (Renault) were 11th and 12th.

Hamilton was out early in the session and set an initial 1m43.899s to bump Renault Friday man and newly-crowned GP2 Series champion Grosjean off the top spot after 20 minutes - the two of them, and Daniel Ricciardo, the first men to set times on the Abu Dhabi layout in 2011.

Hamilton, on his first long run of the weekend, then set about firing in consistent purple sectors for the next 11 laps until he ended up with a 1m41.846s.

Meanwhile, Williams's Rubens Barrichello was forced to park his car at Turn 13 with a serious technical failure. Having a problem this early on, and having completed only three laps, ensured the Brazilian was locked at the bottom of the timesheet.

It was thirty-five minutes into the session before things began to heat up as world champion Vettel moved to second in the times, 1.7s behind the leading McLaren, and a tenth faster than Pastor Maldonado, who was one of the first to try out the option tyres.

This triggered a busy period in the session as the dusty track cleaned up and several top runners posted early improvements - none as fast as Hamilton - to establish an early order of Hamilton, Vettel, Webber, Alonso, Button and Maldonado.

That didn't last long though, as Button found his groove and went just 0.015s slower than the #3 McLaren had done.

Then the Red Bulls fired in fast laps instantly pushing Webber and Vettel to the fore, only for Button to respond again with a 1m40.955s. That lap was half a second quicker than the field, and established him at the top of the order.

With 55 minutes gone Hamilton emerged from the pits for his second, shorter, run and instantly lowered the mark again to a 1m40.466s before heading straight back to his garage. Around the same time Vettel posted a new improvement to go second fastest, 0.341s back, splitting the McLarens. While Massa, who had just improved to fifth behind Webber, spun his Ferrari dramatically at Turn 1.

Just after the hour mark Massa's team-mate Alonso had a similar problem at Turn 5, as Heikki Kovalainen also spun his Lotus under the Yas Hotel. The Spaniard would go off the road again 10 minutes later, indicating that all was not well down in the Scuderia's set-up department.

The frontrunners began bolting on the development soft tyres with 25 minutes to go and Button was the first to move forward - setting a 1m40.263s lap to move ahead of Hamilton at the top of the times. Webber too, improved, but not enough to get ahead of the two McLarens

The Australian went faster still a couple of laps later, in fact, he set the fastest sector one time of anybody, but still the 1m40.412s he produced was not good enough to move him ahead of Button and Hamilton.

There was the usual flurry of activity late-on but Button's time was to stand as only Webber improved significantly. Though this might have been partly due to Vitaly Petrov's late session car failure which left debris on the track and prompted a yellow flag zone in the final sector.

Pos  Driver                Team                    Time              Laps
 1.  Jenson Button         McLaren-Mercedes        1m40.263s           21
 2.  Mark Webber           Red Bull-Renault        1m40.389s  + 0.126  26
 3.  Lewis Hamilton        McLaren-Mercedes        1m40.403s  + 0.140  27
 4.  Sebastian Vettel      Red Bull-Renault        1m40.755s  + 0.492  27
 5.  Fernando Alonso       Ferrari                 1m40.801s  + 0.538  25
 6.  Felipe Massa          Ferrari                 1m41.260s  + 0.997  17
 7.  Adrian Sutil          Force India-Mercedes    1m41.340s  + 1.077  23
 8.  Nico Rosberg          Mercedes                1m42.130s  + 1.867  26
 9.  Paul di Resta         Force India-Mercedes    1m42.151s  + 1.888  28
10.  Jaime Alguersuari     Toro Rosso-Ferrari      1m42.377s  + 2.114  26
11.  Jean-Eric Vergne      Toro Rosso-Ferrari      1m42.633s  + 2.370  26
12.  Romain Grosjean       Renault                 1m42.685s  + 2.422  29
13.  Vitaly Petrov         Renault                 1m43.118s  + 2.855  13
14.  Pastor Maldonado      Williams-Cosworth       1m43.255s  + 2.992  29
15.  Michael Schumacher    Mercedes                1m43.389s  + 3.126  24
16.  Sergio Perez          Sauber-Ferrari          1m44.412s  + 4.149  28
17.  Kamui Kobayashi       Sauber-Ferrari          1m44.484s  + 4.221  18
18.  Heikki Kovalainen     Lotus-Renault           1m44.565s  + 4.302  27
19.  Jarno Trulli          Lotus-Renault           1m44.898s  + 4.635  25
20.  Tonio Liuzzi          HRT-Cosworth            1m46.385s  + 6.122  28
21.  Daniel Ricciardo      HRT-Cosworth            1m46.532s  + 6.269  27
22.  Timo Glock            Virgin-Cosworth         1m48.024s  + 7.761  20
23.  Robert Wickens        Virgin-Cosworth         1m48.551s  + 8.288  23
24.  Rubens Barrichello    Williams-Cosworth                            3

All Timing Unofficial