Championship leader Nico Rosberg outpaced his Mercedes team-mate and nearest title rival Lewis Hamilton to top the times in Friday morning's opening free practice for this weekend's German Grand Prix.
The newly-married 29-year-old German clocked a best lap of one minute and 19.131 seconds to finish ahead of the Briton, who is only four points behind him in the title race, by just 0.065 seconds after 90 minutes action in sizzling heat at the revised Hockenheim circuit.
Two-time champion Fernando Alonso of Spain was third quickest for Ferrari, two-tenths of a second off the pace as the leading the trio led the way in cars adapted to run with revised suspension systems.
Australian Daniel Ricciardo of Red Bull was fourth fastest ahead of Briton Jenson Button in his improved Mercedes and defending four-time champion Sebastian Vettel of Germany in the second Red Bull.
Susie Wolff, the British driver who became the first woman in 22 years to take part in a Grand Prix weekend when she drove briefly at the British event two weeks ago, had better luck this time.
The Williams test driver survived a scare in the opening minutes when she had gearbox problems, but after pitting for repairs went out again and completed 15 laps to record the 15th best time.
This lifted her ahead of both Lotus, both Marussias and both Caterhams, as well as the Sauber of test driver Giedo van der Garde, an impressive effort for someone with so little Formula One experience.