SOCHI, Russia (AP) Williams driver Felipe Massa clocked the fastest time in Friday's second practice session for the Russian Grand Prix, with only six other drivers setting times in heavy rain.
The first practice session was disrupted by a fuel spill and subsequent attempts to clean it up by spraying water, while the second took place with standing water on large parts of the track.
Massa clocked 2 minutes, 0.458 seconds around the Sochi track, two tenths ahead of Ferrari driver Sebastian Vettel. Massa's Williams teammate Valtteri Bottas was third.
''To be P1 is nice even when you are alone on the track,'' said Massa, but acknowledged that he and Williams had learned little about the Olympic Park circuit since dry weather is forecast for qualifying and the race.
''Today is just a loss of time and maybe it was better to keep sleeping a little bit longer,'' he said.
However, Williams' engineering head Rob Smedley said Friday's results suggested the team had made progress on improving its car's wet-weather performance, which has been a problem this season.
''On pure face value, I think we are probably moving forward in that area,'' he said.
In the first session, Force India driver Nico Hulkenberg set a time of 1:44.355, 0.052 seconds faster than Mercedes rival Nico Rosberg, with Vettel third.
The first 30 minutes of that session were lost as track crews cleaned up a diesel fuel spill left by a service vehicle. Vettel called the conditions ''a mess'' over the radio to his team, while organizers said an internal investigation was under way into how the spill happened.
After the Russian fire service used hosepipes to clean up the spilled fuel, much of the track was left wet, slowing cars significantly. Light rain also fell toward the end of the session.
Championship leader Lewis Hamilton of Mercedes was seventh in the first session and only ventured out briefly in the second session without setting a time. He and Massa both span near the end of the first session but neither took damage.
''Since it almost certainly won't rain for the rest of the weekend, we chose not to do a lot of practice in the wet with the risk it gives to the cars,'' Mercedes technical director Paddy Lowe said in a statement.
Fernando Alonso of McLaren, who marks his 250th F1 race this weekend, did the most running of anyone in the second session, notching up 12 laps before a technical problem forced him into the garage.
Alonso is running an upgraded version of McLaren's troubled Honda engine and will almost certainly start from the back of the grid Sunday because of grid penalties for component changes.