Mercedes driver Nico Rosberg (left) topped the rain-hit first day of the second preseason Formula 1 test at Valencia.
The 24-year-old was fastest during the first hour before the rain, setting a best time of 1m20.927sec to shade Scuderia Toro Rosso's Sebastien Buemi by just 0.104sec. Despite topping the times, his day ended badly as he brought out the red flag with 10 minutes remaining after stopping on track on his 58th lap.
Because of the bad weather, drivers' fastest lap times were all set in the first hour, with the new Red Bull RB5 ending near the foot of the times because Mark Webber's lap was posted while the car was still going through the installation process.
The Australian completed 47 laps before being forced to stop on track with an oil leak, and was only able to rejoin the session in the final 15 minutes after repairs. However, the late red flag meant that he could only manage another three laps.
The Force India VJM03 also ran in public for the first time, with Vitantonio Liuzzi driving the car that Adrian Sutil shook down at Silverstone. The Italian was seventh fastest, four seconds off Rosberg's mark, but like Webber the time was set while the car was completing installation laps after missing last week's Valencia test.
"In the dry, the balance felt good," said Liuzzi, who completed 71 laps. "Although when it started to rain it made it more difficult to judge how the car was."
Williams racked up more miles on the Cosworth engine on the powerplant's second full test since 2006. Nico Hulkenberg, who set the third-fastest time when the track was in good shape in the first hour, completed 118 laps and the team reported that it was happy with the progress. Hulkenberg was also one of the fastest drivers in the wet, setting a 1m25.950sec in the penultimate hour before the rain got worse.
Fernando Alonso, on his second appearance in the Ferrari, was fourth fastest. The Spaniard missed most of the morning running after setting his time early on, but the team's hopes that the track would dry were unfulfilled and he completed several longer runs in the afternoon, racking up 88 laps.
Sauber's Kamui Kobayashi also had a restricted program because of the weather, running regularly throughout the day but completing only 55 laps. The Japanese was fifth-fastest overall ahead of Jenson Button, whose McLaren was fitted with some attention-grabbing aero sensor equipment as the team attempted to maximize the data gathered.
Vitaly Petrov completed only 23 laps on his second day in the Renault R30. After setting his fastest time in the first hour, he stayed in the pits until the afternoon, but despite having no mechanical problems the team preferred to limit his track time.
The new Virgin VR-01 made its first public appearance in the hands of German Timo Glock. The team flew out new parts that arrived in Spain on Tuesday night and weren't able to hit the track until the afternoon. After two installation laps, Glock completed a three-lap run in mid-afternoon, setting a best time of 1m38.734sec.
Testing continues tomorrow, with the only scheduled driver change being Michael Schumacher stepping in at Mercedes in place of Rosberg.
Pos Driver Team Time Gap
1. Nico Rosberg Mercedes 1m20.927s
2. Sebastien Buemi Toro Rosso 1m21.031s +0.104
3. Nico Hulkenberg Williams 1m22.243s +1.316
4. Fernando Alonso Ferrari 1m22.895s +1.968
5. Kamui Kobayashi Sauber 1m23.787s +2.860
6. Jenson Button McLaren 1m24.947s +4.020
7. Vitantonio Liuzzi Force India 1m24.968s +4.041
8. Vitaly Petrov Renault 1m25.440s +4.513
9. Mark Webber Red Bull 1m26.502s +5.575
10. Timo Glock Virgin 1m38.734s +17.807