Jenson Button finished the first practice session of the Abu Dhabi Grand Prix on top as McLaren and Red Bull resumed their usual position at the sharp end of the timing sheets.
Button was 0.126s faster than Red Bull's Mark Webber with McLaren's Lewis Hamilton third fastest, just 0.014s further adrift. Sebastian Vettel was fourth fastest, 0.492s off Button, but came across traffic in the final sector of his fastest lap.
However, the times should be treated with caution as all the fastest lap times were set on a development tyre, brought to Abu Dhabi this weekend so that Pirelli can gather data for next year. The drivers also used the medium tyre, which will be used this weekend, but tended to be over a second slower on the harder rubber.
Ferrari's Fernando Alonso left his run on the development tyres to the last few minutes after a long, and at times torturous, run on the mediums. He finished the session within touching distance of Vettel and 0.538s off Button, but at one stage spent more time off the track than on it.
Ferrari is using the Friday practice sessions to focus on its development parts for 2012, but clearly there was some sort of problem as both drivers struggled to keep the rear of their cars in check midway through the 90 minute session. Alonso eventually resorted to skipping the turn eight and nine chicane completely so that he did not have to deal with the snappy rear end under braking. Team-mate Felipe Massa experienced similar problems and was over 0.4s off the pace of Alonso by the end of the session in sixth.
Adrian Sutil maintained his strong form from the Indian Grand Prix by setting the seventh fastest time and getting within a tenth of Massa's best. Mercedes' Nico Rosberg was a further 0.790s slower than the Force India in eighth, just ahead of Sutil's team-mate Paul di Resta who rounded off a solid first session for the Indian team. Jaime Alguersuari was tenth overall in the Toro Rosso, 2.114s off Button's pace.
It was also a good morning for new boys Jean-Eric Vergne and Romain Grosjean, who lined up 11th and 12th in the Toro Rosso and Renault respectively. Both were subbing in for the morning and had very productive sessions, with Vergne completing 26 laps and Grosjean 29. Grosjean also outperformed his team-mate Vitaly Petrov, although it should be noted that the Russian completed just 13 laps before what looked like an engine problem at the end of the session.
Rubens Barrichello was also troubled by reliability problems as his Williams suffered an oil pressure issue after just three laps. The car was recovered to the pits, but the team didn't have enough time to get him back out.