Sebastian Vettel set the pace in Friday's second practice in Valencia, which gave the first indication of how qualifying on the soft tyres could pan out.
Romain Grosjean posted the session's first time, a 1:45.049, but that was quickly beaten by Pastor Maldonado and then Kamui Kobayashi while Sebastian Vettel had a brief spell at the top before Jenson Button went quickest as 18 drivers set times in the first ten minutes.
The timesheets continued to change with Maldonado returning to the front only to lose out to Button, who in turn lost out to Lewis Hamilton, who then lost out to Fernando Alonso. The Spaniard dropped the benchmark time to a 1:40.248.
The battle for the P1 slot, though, was by no means over with Michael Schumacher taking it minutes later as the track quietened down with many of his rivals back in the pits after their first runs. It was a 1:40.169 for the German.
Half an hour into the session Jenson Button was the first of the frontrunners to try the softer option Pirellis and went quickest. But he was still beaten by Nico Rosberg on the mediums. Button's move, though, prompted others to venture out on what should be the quicker rubber.
Alonso was the next to lead the way with a 1:39.773 while Pedro de la Rosa became the first crasher of the weekend as he understeered off the track at Turn 14 causing front left damage.
With the yellow flags lifted, Schumacher went a tenth quicker than anyone else but soon lost out to Vettel while Nico Hulkenberg was second quickest for Force India. The wo younger Germans at the top before the field switched to heavier fuelled runspate of low fuel soft tyres runs ended with the ts.
That's how the session ended, with the drivers on heavy fuel loads and Vettel in the P1 slot. It must be noted, though, that on the heavy fuel loads Grosjean appeared to have the better pace of the field although the leading teams were close.
01 Sebastian Vettel Red Bull 1:39.334 33 laps
02 Nico Hulkenberg Force India 1:39.465 0.131 32 laps
03 Kamui Kobayashi Sauber 1:39.595 0.261 20 laps
04 Michael Schumacher Mercedes 1:39.601 0.267 27 laps
05 Bruno Senna Williams 1:39.644 0.310 34 laps
06 Paul di Resta Force India 1:39.700 0.366 32 laps
07 Fernando Alonso Ferrari 1:39.733 0.399 34 laps
08 Romain Grosjean Lotus 1:39.868 0.534 33 laps
09 Mark Webber Red Bull 1:39.901 0.567 30 laps
10 Nico Rosberg Mercedes 1:39.926 0.592 32 laps
11 Kimi Raikkonen Lotus 1:39.945 0.611 34 laps
12 Jenson Button McLaren 1:39.990 0.656 33 laps
13 Pastor Maldonado Williams 1:40.075 0.741 29 laps
14 Lewis Hamilton McLaren 1:40.147 0.813 25 laps
15 Felipe Massa Ferrari 1:40.244 0.910 35 laps
16 Sergio Perez Sauber 1:40.511 1.177 29 laps
17 Vitaly Petrov Caterham 1:40.963 1.629 20 laps
18 Daniel Ricciardo Toro Rosso 1:41.121 1.787 32 laps
19 Heikki Kovalainen Caterham 1:41.197 1.863 38 laps
20 Jean-Eric Vergne Toro Rosso 1:41.263 1.929 29 laps
21 Timo Glock Marussia 1:42.424 3.090 21 laps
22 Charles Pic Marussia 1:42.958 3.624 30 laps
23 Narain Karthikeyan HRT 1:44.201 4.867 33 laps
24 Pedro de la Rosa HRT 1:44.260 4.926 12 laps