The Mexican, who had reached the lunchbreak on top thanks to his 1m22.094s lap on soft Pirelli rubber, joined most of the rest of the field in concentrating on race simulations with heavy fuel loads during the afternoon.

Jenson Button was one of the few drivers not to undertake a long run in the afternoon. The McLaren driver made the most of medium compound tyres and a lower fuel load to climb to second place, only 0.009 seconds adrift of Perez.

Daniel Ricciardo (Toro Rosso) completed the most laps of anybody - 130 - and this included an impressive 35-lap stint on a succession of sets of soft tyres. A further run of a similar distance was shortened by the onset of mid-afternoon rain. The track did not dry enough to enable anybody to switch back to slicks before the end of the day.

Felipe Massa was fourth fastest in the Ferrari and was, like Ricciardo, one of the few to take to the track on intermediate rubber during the height of the rain. Paul di Resta was next up for Force India, the British driver just managing to finish his 52-lap race simulation as the rain began to fall.

There was only one flag during the afternoon, caused when Bruno Senna stopped on the approach to the La Caixa hairpin. The Williams driver was sixth fastest.

Behind him were Heikki Kovalainen's Caterham and the Red Bull of Mark Webber - which completed just a single run of more than five laps during the entire day.

Propping up the timesheets were Mercedes driver Nico Rosberg and Lotus man Kimi Raikkonen. The 2007 world champion lost over an hour during the morning while an issue with his steering was rectified and only completed 43 laps during the day.

TODAY'S TIMES

Pos  Driver         Team            Time                Laps
 1.  Perez          Sauber          1m22.094s           114
 2.  Button         McLaren         1m22.103s  +0.009   44
 3.  Ricciardo      Toro Rosso      1m22.155s  +0.061   131
 4.  Massa          Ferrari         1m22.413s  +0.319   122
 5.  Di Resta       Force India     1m22.446s  +0.352   108
 6.  Senna          Williams        1m22.480s  +0.386   111
 7.  Kovalainen     Caterham        1m22.630s  +0.536   64
 8.  Webber         Red Bull        1m22.662s  +0.568   70
 9.  Rosberg        Mercedes        1m22.932s  +0.838   129
10.  Raikkonen      Lotus           1m25.379s  +3.285   43

Autosport.com