Kimi Raikkonen set the pace ahead of Sebastian Vettel before the rain came down in Friday's second practice for the Malaysian GP.
With rain threatening, the drivers were quickly into the action with Jean-Eric Verge setting the first P1 time. Two minutes later, though, he was down in seventh place and two seconds off the pace such was the franetic nature of the early minutes in FP2.
Fernando Alonso had a turn in the P1 slot before losing out to Kimi Raikkonen, who posted a 1:37.042. Behind them was Sebastian Vettel, Felipe Massa and Mark Webber.
Meanwhile, Sauber rookie Esteban Gutierrez headed back into the pits after an extinguisher discharged in his car. It was reportedly caused by an exhaust issue.
Just 20 minutes in to the session - with reports of rain ten minutes down the line - the drivers begun to switch to the quicker medium tyres.
Massa hit the front with a 1:36.661 while Alonso climbed to second, 0.324s behind his team-mate. Jenson Button improved from 20th on the hards to eighth on the mediums. The two Red Bulls also made the swap with Vettel hitting the front with a 1:36.588, which was 0.073s up on Massa. Mark Webber improved to fourth.
After that it was the two Lotus drivers, the two Force India drivers, the two McLarens and the two Saubers. The two-by-two, though, changed when Raikkonen hit the front, overhauling Vettel by 0.019s. The Mercs also entered the mix as, having been focused on race set-up, they put in some quicker laps with Nico Rosberg taking seventh and Lewis Hamilton ninth.
The rain, which had thrown down a drop or two, begun to fall a bit heavier in some parts of the circuit with 40 minutes to go. However, the asphalt was so hot it had little impact at first.
Nico Hulkenberg was the first to get caught out when it came down harder and found himself on the grass down the road leading into the pits. Thankfully he got his car pointing the right way and did not collect Vettel as his fellow German made his way back into his dry garage.
After a brief lull the drivers strapped on the intermediate tyres and headed back out. With the track dry in some parts and very wet in others, drivers slipped and slid with Esteban Gutierrez getting the first off. He was followed by Sergio Perez as the drivers were lapping about 20s slower than their previous bests.
Although the track dried out as the clock counted down and the drivers returned to the slick tyres, it was never dry enough to launch an assault of Raikkonen's P1 time. He finished the session 0.019s up on Vettel.
01 Kimi Raikkonen Lotus 1:36.569
2 Sebastian Vettel Red Bull 1:36.588 +0.019
3 Felipe Massa Ferrari 1:36.661 +0.092
4 Fernando Alonso Ferrari 1:36.985 +0.416
5 Mark Webber Red Bull 1:37.026 +0.457
6 Romain Grosjean Lotus 1:37.206 +0.637
7 Nico Rosberg Mercedes 1:37.448 +0.879
8 Paul di Resta Force India 1:37.571 +1.002
9 Lewis Hamilton Mercedes 1:37.574 +1.005
10 Adrian Sutil Force India 1:37.788 +1.219
11 Sergio Perez McLaren 1:37.838 +1.269
12 Jenson Button McLaren 1:37.865 +1.296
13 Nico Hulkenberg Sauber 1:38.068 +1.499
14 Esteban Gutierrez Sauber 1:38.645 +2.076
15 Jean-Eric Vergne Toro Rosso 1:38.738 +2.169
16 Pastor Maldonado Williams 1:38.801 +2.232
17 Daniel Ricciardo Toro Rosso 1:38.904 +2.335
18 Jules Bianchi Marussia 1:39.508 +2.939
19 Valtteri Bottas Williams 1:39.660 +3.091
20 Charles Pic Caterham 1:40.757 +4.188
21 Giedo van der Garde Caterham 1:40.768 +4.199
22 Max Chilton Marussia 1:41.438 +4.869
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