Lewis Hamilton has insisted that he is "not particularly worried" about his performances in this afternoon's two practice sessions ahead of the German Grand Prix.

Hamilton was slower than championship rival and teammate Nico Rosberg in both sessions as Mercedes once again dominated.

The Englishman has won five of the last six races to turn a 43-point deficit into a six-point lead over Rosberg, but he admits that he will need to improve on Sunday if he is maintain the advantage.

"I hope I can get my act together tomorrow. It was just not a great lap, so I am not particularly worried," the reigning champion told reporters.

"FP2 didn't feel very good. It got worse and worse with some balance issues, but I will rectify it for tomorrow.

"Overnight we should be in a good position, and tomorrow it should be close as Nico is pretty quick here. He is feeling quite confident and calm in the car."

The practice sessions also saw Hamilton's compatriot Jenson Button taken to hospital due to an eye complaint.