Final practice - Rosberg heads a Williams one-two 20 Jun 2009
Nico Rosberg and Kazuki Nakajima put Williams first and second in Saturday morning's final practice session at Silverstone, making it harder still to predict form for qualifying this afternoon.
The Japanese driver had just upped the ante with a lap of 1m 19.102s when the German became the only man to dip below 1m 19s with 1m 18.899s.
Jarno Trulli was third for Toyota in 1m 19.125s, then came Fridays pacesetter Sebastian Vettel on 1m 19.371s for Red Bull. Team mate Mark Webber was only ninth, on 1m 19.946s.
Between them were the Ferraris of Felipe Massa and Kimi Raikkonen with 1m 19.596s and 1m 19.855s respectively, Toyota's Timo Glock on 1m 19.868s and Renault's Fernando Alonso with 1m 19.917s.
The Brawns? They appeared still to be conducting mainly race work, with Rubens Barrichello 10th on 1m 20.028s and Jenson Button 12th on 1m 20.157s. Between them sat McLaren's Lewis Hamilton on 1m 20.048s, and behind Button Renault's Nelson Piquet (1mn 20.232s) headed Toro Rosso's Sebastien Bourdais (1m 20.459s), the Force Indias of Adrian Sutil (1m 20.548s) and Giancarlo Fisichella (1m 20.572s), McLaren's Heikki Kovalainen (1m 20.638s) and BMW Sauber's Nick Heidfeld (1m 20.696s).
Sebastien Buemi just failed to break 1m 21s with 1m 21.024s for Toro Rosso, and Robert Kubica brought up the rear with 1m 21.039s in the second BMW Sauber.
The session started on a damp track, but with 20 minutes gone it had pretty much dried and similar conditions are expected to prevail for qualifying.