Fernando Alonso set the pace on a drying Barcelona circuit after heavily rain made for a wet start to Friday's first practice.
It was a cold and wet start to the weekend as the rain came down and the track temperature dropped to 17'C. As a result of the conditions - and everyone's prior knowledge of the track - it was a slow start to the morning with Nico Hulkenberg, whose Sauber sported a new front wing, the first to set a time, a 1:51.644. He took three seconds off on his next lap but was the only driver to post a time in the first 30 minutes.
Felipe Massa was the next to clock a time and hit the front with his 1:45.023 before he was overhauled by Lotus driver Romain Grosjean. With the track notably drying out, more drivers ventured out with Fernando Alonso the next to lead the way to great applause from the Spanish fans. It was a 1:43.630 for the Ferrari driver.
Grosjean returned to the P1 slot but his stay was brief as Jean-Eric Vergne went quickest before he lost out to his Toro Rosso team-mate Daniel Ricciardo. The Australian lowered the benchmark to a 1:42.605 but was soon dropped by Mark Webber while Kimi Raikkonen took second.
With 30 minutes to go - and the drivers still on the intermediate tyres - Hulkenberg reported to his Sauber that "there are quite a few dry patches now, it's getting harder for the tyres."
That, though, didn't stop Alonso from retaking the P1 spot although ten minutes later he lost it to Lewis Hamilton. The Mercedes driver, who is adamant the cooler temperatures in Spain will help Mercedes, crossed the line with a 1:36.159.
The final 20 minutes saw a swap to the slick tyres with Vergne the first to try the prototype Pirelli hard. He went fifth on his first flying lap and quickest on his next with a 1:34.710. Massa, still on the intermediates, was second quickest ahead of Hamilton and Alonso. Ricciardo followed his team-mate out by used the race hard tyres, ie the ones that will actually be used this weekend. He immediately went quickest with a 1:29.602 - five seconds quicker than his team-mate!
Ricciardo lowered the benchmark on his next lap but couldn't stop both Hamilton and Alonso from edging him before Bottas edged them. A 1:26.456 from the Williams rookie. However, as the conditions continued to improve almost every passing lap put another driver in the P1 slot.
The session eventually concluded with Alonso on top with a 1:25.252. Massa was second, 0.203s down, while Vergne was third.
01 Fernando Alonso Ferrari 1:25.252 20 laps
02 Felipe Massa Ferrari 1:25.455 +0.203 20 laps
03 Jean-Eric Vergne Toro Rosso 1:25.667 +0.415 25 laps
04 Romain Grosjean Lotus 1:26.042 +0.790 21 laps
05 Adrian Sutil Force India 1:26.212 +0.960 24 laps
06 Lewis Hamilton Mercedes 1:26.374 +1.122 19 laps
07 Valtteri Bottas Williams 1:6.456 +1.204 20 laps
08 Kimi Raikkonen Lotus 1:26.614 +1.362 21 laps
09 Nico Rosberg Mercedes 1:26.621 +1.369 21 laps
10 Paul di Resta Force India 1:26.755 +1.503 16 laps
11 Daniel Ricciardo Toro Rosso 1:26.940 +1.688 26 laps
12 Nico Hulkenberg Sauber 1:27.061 +1.809 24 laps
13 Sergio Perez McLaren 1:27.135 +1.883 6 laps
14 Esteban Gutierrez Sauber 1:27.250 +1.998 26 laps
15 Pastor Maldonado Williams 1:27.576 +2.324 24 laps
16 Giedo van der Garde Caterham 1:28.600 +3.348 19 laps
17 Jules Bianchi Marussia 1:28.887 +3.635 14 laps
18 Heikki Kovalainen Caterham 1:29.177 +3.925 14 laps
19 Sebastian Vettel Red Bull 1:29.457 +4.205 11 laps
20 Mark Webber Red Bull 1:29.473 +4.221 21 laps
21 Rodolfo Gonzalez Marussia 1:30.314 +5.062 12 laps
22 Jenson Button McLaren no time 6 laps
Gallery: The Rain Is Spain