Russian GP: Nico Hulkenberg tops disrupted first practice

What was described by the FIA as "a significant diesel spillage" on track shortly prior to the start of FP1 resulted in a 30-minute delay.

With the circuit being prepared for action, a tanker suffered a failure that resulted in the spill through turns eight and nine.

Initial attempts to cover the diesel with cement dust proved fruitless, which forced the marshals into a more thorough clean-up operation as they washed down the asphalt.

Once the action finally got under way the installation laps took place primarily on intermediates to cope with the wet part of the track, with Williams duo Felipe Massa and Valtteri Bottas even opting for full wets.

There were, however, further issues for the 20-strong field to contend with as most complained of the track being very dusty in the dry parts, and in turn slippery where the washed sections were slow to dry out.

Fernando Alonso was the first to post a timed lap 20 minutes into the shortened hour-long session, stopping the clock at a fraction just over two minutes on what was a very tentative outing on soft tyres.

Gaining in confidence Alonso swiftly lowered that mark by seven seconds over the next two laps before Sauber's Marcus Ericsson embarked on a steady run of laps to move within four tenths of a second of the Spaniard.

Alonso's team-mate Jenson Button then set a slightly more representative time soon after of 1:50.920s before spots of rain threatened to add to mix of a disrupted session.

But the rain forecast for FP2 held off, ensuring for the last 10 minutes of the session at least there was some meaningful running.

Come the conclusion it was Hulkenberg who led the way with a lap of 1:44.355s, a full second off the best FP1 time from Mercedes' Nico Rosberg a year ago ahead of the debut Russian race.

It was Rosberg who had to settle for second best, finishing just 0.052s adrift, with Sebastian Vettel third quickest in his Ferrari, 0.631s off the pace.

The German was followed by the second Force India of Sergio Perez and then Daniel Ricciardo in his Red Bull, the Australian the only other driver to finish within a second of Hulkenberg.

Toro Rosso's Carlos Sainz Jr was sixth quickest, 1.133s back, followed by Lewis Hamilton in his Mercedes a further two tenths of a second down, and with the reigning champion incurring a late spin at the penultimate corner on what would have been a faster lap.

Valtteri Bottas, Max Verstappen and Kimi Raikkonen completed the top 10, the latter 1.860s adrift.

Button finished 11th and Alonso 14th, the duo sandwiching Felipe Massa and Felipe Nasr.

Lotus reserve Jolyon Palmer, standing in for Haas-bound Romain Grosjean, was down in 17th, 4.7s back, with Will Stevens bringing up the rear for Manor, with the Briton almost 14 seconds behind.

FP1 RESULT