Felipe Massa topped the times on a damp third day of testing at Barcelona in Spain on Wednesday, despite a minor off in the morning.
Teams had hoped for improved weather conditions but rain in the morning ensured the track would be damp for the entire day.
Massa, running revised aerodynamics on the Ferrari, set a lap that was six tenths of a second faster than Red Bull Racing's Mark Webber, whose RB4 continued to lead the chasing pack of cars.
It was not all plain sailing for Massa, however, after he slid off the track at Turn 12 just before midday. There was no damage to the car, however, and the Brazilian was able to resume testing shortly afterwards.
Ferrari test driver Luca Badoer was third fastest, ahead of David Coulthard in the Red Bull Racing car and Fernando Alonso in the Renault.
Nico Rosberg ended up sixth quickest overall, with his Williams team deciding to make the most of the poor track conditions to practice pi stops.
The German completed around 20 stops over the day, as well as completing long runs, with teammate Kazuki Nakajima also putting in some pitstop practice earlier in the day.
Toyota's Timo Glock brought out the second red flag of the day when he went off the track at Turn 1 shortly after 4pm. His car kissed the barriers on the left-hand side of the circuit, but without major damage.
"That was only half a day's work for me today because the morning was too wet for us to gain anything from testing," said Glock. "In the afternoon we did some running in the wet conditions - first on heavy wet tyres, changing to standard wet tyres.
"The track conditions changed quite a lot as the track dried out but not enough. It was difficult to draw conclusions but we found a similar picture to the dry which will help us define where we concentrate our work. We have a few more days of testing to work out how to move forward so we will push hard."
McLaren had been due to run today but decided not to waste their mileage because of the weather.
Pos Driver Team Time Laps 1. Massa Ferrari (B) 1:30.673 46
2. Webber Red Bull-Renault (B) 1:31.213 43
3. Badoer Ferrari (B) 1:31.288 33
4. Coulthard Red Bull-Renault (B) 1:31.654 44
5. Alonso Renault (B) 1:31.731 28
6. Rosberg Williams-Toyota (B) 1:31.963 97
7. Glock Toyota (B) 1:32.407 33
8. Trulli Toyota (B) 1:32.571 47
9. Hulkenberg Williams-Toyota (B) 1:33.102 53
10. Nakajima Williams-Toyota (B) no time 33
11. Piquet Renault (B) no time 1
All Timing Unofficial