Nico Rosberg edges Lewis Hamilton in German Grand Prix practice
Nico Rosberg headed team-mate Lewis Hamilton as Mercedes dominated first practice at the German Grand Prix.
Rosberg was 0.326 seconds quicker than Hamilton at Hockenheim, which hosts a race for the first time in two years.
Ferrari's Sebastian Vettel was third - but 1.150 seconds off the pace.
Kimi Raikkonen's Ferrari was fourth, ahead of the Red Bulls of Max Verstappen and Daniel Ricciardo and McLaren's Fernando Alonso and Jenson Button.
On a warm and sunny morning in the Rhineland, it was a largely uneventful session, although Williams' Valtteri Bottas had a spin and Haas' Romain Grosjean nearly rammed the back of Vettel's Ferrari in a misunderstanding at the penultimate corner.
And many drivers ran wide at the fast Turn One as they explored the track's and their cars' limits.
Grosjean also went off in the gravel run-off at Turn Eight late in the session but was able to rejoin.
And the return of radio communications, on which restrictions were removed following a meeting of the strategy group of senior bosses on Thursday, was notable for the increased number of messages during the session.
Hamilton, who appeared slightly out of sorts and was never on a par with his team-mate throughout the 90 minutes, is determined to win this weekend to maximise his advantage ahead of the four-week summer break that follows the race.
The Briton took the championship lead for the first time this season with victory in Hungary last weekend but knows he will be starting one of the first two races after the break from the back of the grid as a result of penalties for using too many engine parts.
He says the psychological appeal of beating Rosberg at his home race was not of interest.
"Not really," Hamilton said. "It's just a race to me. It makes no difference. The goal is to be in a good position going into the break."
McLaren's performance was again an encouragement and indicative of their general upward slope - Alonso, on his 35th birthday, was just 0.256secs slower than Verstappen.
Button was 0.429secs slower than his team-mate and complaining of both understeer - poor front-end grip - and lack of traction.
Completing the two-by-two nature of the session, Toro Rosso's Daniil Kvyat and Carlos Sainz were ninth and 10th.