Poland's Robert Kubica was fastest for BMW Sauber in today's final free practice for tomorrow''s European Grand Prix at the new Valencia street circuit.

The 23-year-old driver from Krakow lapped in one minute and 38.754 seconds to top the timesheets on a humid and overcast morning after heavy overnight rain.

The slightly cooler conditions encouraged drivers to set fast times, but few were pushing to the limit before today's qualifying session in the knowledge that one error could cause serious damage on such a track.

German Nico Rosberg in a Williams was second fastest, one-tenth of a second behind Kubica with Frenchman Sebastien Bourdais third in a Toro Rosso and Rosberg's Williams team-mate Japanese Kazuki Nakajima fourth.

The likely frontrunners concentrated on conservation of their tyres for qualifying and tomorrow's 57 laps around the 5.42-kms Mediterranean harbour circuit.

Brazilian Felipe Massa, in a Ferrari, was the quickest of the title challengers in fifth place.

His team-mate and world champion Kimi Raikkonen was 15th and one behind fellow-Finn Heikki Kovalainen, winner of the Hungarian Grand Prix three weeks ago for McLaren.

Championship leading Briton Lewis Hamilton clocked the seventh best time in the other McLaren behind German Sebastian Vettel's Toro Rosso.

Double world champion Spaniard Fernando Alonso was also among those not pushing for a fastest lap time and wound up 13th for Renault.

All of the drivers in the top 10 clocked times that were faster than that set by Raikkonen when he topped the times in yesterday's second free practice session.