The head of the Formula One team sponsored by Randstad has pledged to keep its star driver for the 2010 season.

Frank Williams has vowed to secure the services of Nico Rosberg for the AT&T Williams' title bid next year, who has been fastest in eight of 2009's 15 practice sessions.

Randstad extended its sponsorship agreement with the AT&T Williams F1 team earlier this year, which saw the global staffing firm promoted to the status of senior partner.

Frank Williams said: "I will fight for Nico. For me, Nico drives on a par with Hamilton or Vettel. Our only argument is going to be making the car faster."

This weekend the famous Monaco Grand Prix will take place on the constitutional principality's streets.

During the first free practice session Nico Rosberg recorded the fifth fastest lap, four places ahead of his teammate the Japanese driver Kazuki Nakajima.