(CNN) -- Australian Mark Webber set the pace in practice for Sunday's British Grand Prix at Silverstone on a good day for the Red Bulls.
Webber, fourth fastest in the morning session, recorded a time of one minute 31.234 seconds with two-time world champion Fernando Alonso of Spain next best for Ferrari.
German Sebastian Vettel in the second Red Bull was third fastest, with less than seven-tenths of a second separating the top three drivers, but championship leader Lewis Hamilton was only eighth best in his McLaren.
On a tricky afternoon, with blistering track temperatures many drivers struggled for grip, Hamilton included, who went off at the Becketts and Abbey corners.
Both Ferraris drivers went off-course at Copse, while Felipe Massa also spun at Brooklands.
Hamilton's teammate Jenson Button, the reigning world champion, finished 13th quickest as both the McLarens appeared to struggle with the setup of their car after recent modifications.
Massa was fourth best in the second Ferrari ahead of Mercedes drivers Germans Nico Rosberg and Michael Schumacher who were fifth and sixth quickest respectively.
Russian Vitaly Petrov of Renault was seventh quickest.
Official qualifying to decide grid positions takes part on Saturday afternoon.