Nico Rosberg raised the stakes in his duel with Lewis Hamilton when he bounced back to top the times on Saturday ahead of his Mercedes team-mate in the third and final free practice session ahead of the German Grand Prix.
The 29-year-old world championship leading German, who has never won or even been on the podium at his home race, delivered a near-perfect lap of one minute and 17.779 seconds to take the initiative in the final minutes.
That was enough to lift him six-tenths clear of Briton Hamilton, 29, the 2008 champion, who followed him on track, but was unable to match his lap time on another very hot morning at Hockenheim where the track temperature rose to 48 degrees Celsius.
Rosberg leads Hamilton by four points, following the Briton's home win at Silverstone two weeks ago, and is seeking to complete a memorable week, in which he has seen Germany win the World Cup, married his long-term girlfriend and signed a new contract, with a home triumph.
Hamilton's lap in pursuit was affected by traffic and braking problems, but the big gap between them demonstrated that Rosberg, at his best, can produce lap times that are a major challenge to Hamilton's flair and speed.
Two-time champion Fernando Alonso of Ferrari was third fastest, endorsing his potential at Hockenheim where the Spaniard has enjoyed three career wins and won for the last time two years ago. He recovered coolly, too, after a big spin at Turn Eight during the session.
Brazilian Felipe Massa of Williams was fourth fastest ahead of his team-mate Finn Valtteri Bottas, Danish rookie Kevin Magnussen of McLaren, Australian Daniel Ricciardo of Red Bull and Finn Kimi Raikkonen, eighth for Ferrari despite a session dogged by fuel-supply problems.