Mark Webber blitzed the competition at Barcelona on Thursday as the Red Bull racer proved he had pace no matter the conditions.
Wet and intermediate tyres were the order of the morning as the rain came down at the Circuit de Catalunya
The day began with a brief tussle between Webber and Felipe Massa with the top honours as the duo had the better of the early running.
Jean-Eric Vergne joined the battle in his Toro Rosso but it was Lewis Hamilton in the Mercedes who led the way at the lunch interval. The Brit's time was a 1:41.614 while Massa was second.
The action resumed after lunch with a definite dry line appearing and less spray rising from the back of the cars.
Webber in his RB9 returned to the front but with the conditions improving with every minute, the lap times tumbled in the final two hours.
Esteban Gutierrez, Valtteri Bottas and Hamilton all had a turn in the P1 slot but at the end of a mad flurry of activity in the final 20 minutes it was Webber who at the top with a 1:22.693 set on the soft Pirelli tyres.
Hamilton, on the medium Pirellis, was second 1.655s off the pace while Vergne, who was P3, was a massive 2.324s down.
Bottas finished in fourth place ahead of McLaren driver Sergio Perez and Gutierrez. They were also the last drivers to get within four seconds off Webber's P1 time.
Despite the conditions there were only three red flags throughout the day.
The first was in the morning when Romain Grosjean spun off at Turn 12 while the second was just before lunch when Gutierrez made contract with the barriers at Turn 3, damaging the front of his Sauber C32.
The third came late in the day when Massa's F138 ground to a halt at Campsa.
01 Webber Red Bull 1:22.693 90 laps
02 Hamilton Mercedes 1:24.348 +1.655 113 laps
03 Vergne Toro Rosso 1:25.017 +2.324 59 laps
04 Bottas Williams 1:26.458 +3.765 85 laps
05 Perez McLaren 1:26.538 +3.845 100 laps
06 Gutierrez Sauber 1:26.574 +3.881 92 laps
07 di Resta Force India 1:27.107 +4.414 57 laps
08 Massa Ferrari 1:27.541 +4.848 112 laps
09 Chilton Marussia 1:28.166 +5.473 78 laps
10 Pic Caterham 1:28.644 +5.951 83 laps
11 Grosjean Lotus 1:34.928 +12.235 52 laps
Testing Resumes At Barcelona