SOCHI - Formula One fans endured more spills than thrills at the Russian Grand Prix on Friday after a cleaning truck leaked diesel across the circuit before first practice and rain washed out the afternoon session.

Force India's Nico Hulkenberg eventually topped the morning timesheets while Felipe Massa was fastest for Williams after lunch. Neither session offered much for the crowd sheltering in the stands, let alone those viewing from afar, with only eight drivers setting a lap time in the afternoon. The Mercedes drivers, whose team could clinch their second successive constructors' title on Sunday, failed to set a time after lunch. They did at least achieve that in the first session, however, with world champion Lewis Hamilton leaving it until the last five minutes to complete a lap and ending up seventh on the timesheets.

Hulkenberg led a practice session for the first time this season after banging in a quick lap right at the finish, 0.052 quicker than Mercedes' Nico Rosberg, for a best time of one minute 44.355 seconds. Hamilton, who leads team mate Rosberg by 48 points with five races remaining, had been second fastest with two minutes to go as the track got quicker and would have been faster without a late spin.

The opening 90 minute session was reduced to an hour as workers hosed and cleansed the track following the 'significant' spillage from a truck that had been supposed to sweep the asphalt. When drivers did go out, on wet tyres, it was on a slippery track with ominous rainclouds replacing the early morning sunshine.

"What a mess," exclaimed Ferrari's Sebastian Vettel, who was third fastest in the morning and second in the afternoon, over the team radio after driving through the affected turns seven and eight. "It is really slippy," agreed Sauber's Swedish driver Marcus Ericsson.

No time was set for the first 20 minutes before McLaren's Fernando Alonso, who will start from the back of the grid due to penalties for engine changes following a Honda upgrade, got things rolling. The rain then set in for the afternoon, with Massa splashing around in a best time of 2:00.458.