Nico Rosberg has given his Formula 1 employers' Williams a clear ultimatum that should the team's form not improve markedly in 2009, he will not hang around - as he bids to save a grand prix career in serious danger of hitting the skids.

Despite having registered his first two podium finishes in the top flight this year - with third position in the season curtain-raiser Down Under in Melbourne and then an inspired charge to the runner-up spot in the sport's inaugural night race in Singapore in September - and qualified six times inside the top eight, Rosberg endured a generally dispiriting 2008 campaign at the Grove-based outfit, winding up a lowly 13th in the final drivers' standings.

Aside from his brace of impressive rostrums, there were just three further single-point finishes for eighth place along the way as Williams' development patently failed to keep pace with that of its immediate rivals and the squad ultimately ended the campaign just eighth in the constructors' title chase.

Moreover, on three occasions Rosberg even failed to break out of the dreaded Q1 in qualifying, and he has admitted that his F1 career is currently stuck in neutral whilst those of former junior category sparring partners Lewis Hamilton and Robert Kubica amongst others are accelerating rapidly up through the gears [see separate story - click here].

Though McLaren-Mercedes made overtures to secure his services in place of the departing Fernando Alonso at the end of 2007, the 23-year-old remained loyal to 16-time former world champions Williams for a third consecutive term. That loyalty, he stresses, is now close to breaking point.

When asked when he will decide where he wishes to drive in 2010 and beyond, Rosberg told Dutch website Formule 1 Race Report 'by the middle of the coming season'.

"If Williams are still not there, then I will have to think about somewhere else," he urged. "I have to think of my own career.

"There are other options for me, but if I wait for too long, those doors obviously close."