Johannesburg, July 30 : Nico Rosberg completed a clean sweep by dominating all three practice sessions ahead of Mercedes teammate and reigning world champion Lewis Hamilton for Sunday's German Grand Prix.
Rosberg, who won his last Formula One race on the Hockenheim course two years ago, posted a best lap of 1min15.738 seconds to nudge ahead of Hamilton, Sport24 reported.
Meanwhile, Hamilton could face a penalty ahead of qualifying after being called to the stewards over 'unsafe release'.
The Brit seemed to have been unsafely released from in the pit-lane in front of Haas driver Romain Grosjean.
Red Bull's Daniel Ricciardo was third fastest ahead of Finn Kimi Raikkonen and his Ferrari team mate Sebastian Vettel.
Hamilton currently holds a six-point lead over Rosberg at the top of the standings after winning the Hungarian Grand Prix last Sunday, which was his consecutive fifth win of the season.