BERLIN, Feb 5, 2008 (AFP) - Williams director Patrick Head has said he expects good things from driver Nico Rosberg this season and was glad the talented German was not lured to McClaren Mercedes.

Rosberg, 22, ended up ninth in his second Formula One season in 2007, where his best finish was fourth place in October´s Brazilian Grand Prix, but Head, the team´s engineering director, said the German will just get better.

"Nico is a philosopher, he has decided to become a successful driver, just as we have decided to become a successful team, we are striving to improve our engine," Head told German agency SID.

Rosberg had been linked to the vacant drivers seat at McClaren Mercedes following Fernando Alonso´s departure at the end of last season, so Head was pleased the German has stayed after Finland´s Heikki Kovalainen was signed by the McClaren team.

"He was the best driver for us in 2007 and got good results for us, it was always obvious to us we could not let him go," said Head.

With Rosberg under contract for another two seasons, Head says the Williams team, with Japan´s Kauki Nakajima as the other driver, must strive to improve their engine to give their drivers the best chance of success this season.

And Head says he is impressed with the attitude of Rosberg, the son of the former Formula One world champion Keke Rosberg.

"Nico does not think: I am the best and I will always be good," said Head.

"He is constantly looking to improve.

"We always knew Nico was fast, but he is constantly performing well on all levels."