Williams have unveiled their 2009 challenger, the FW31, at the Portimao circuit.
The team are relying on the new car to revive their fortunes after a disappointing 2008 season, but have cause for optimism having switched their attention to this season's radical new rules earlier than many of their rivals.
They have also taken the unique decision to produce their own flywheel-based Kinetic Energy Recovery System, in contrast to the battery devices that the rest of the teams have developed.
Test driver Nico Hulkenberg will give the car its initial test at Portimao today.
The FW31 has been revealed in an interim winter testing colour scheme, with the definitive 2009 livery to be unveiled in February.