The Williams FW33 was a Formula One racing car developed by Williams F1 for the 2011 Formula One season. It was driven by Brazilian veteran Rubens Barrichello and 2010 GP2 Series champion and rookie driver Pastor Maldonado. The car was shaken down at Silverstone on 28 January 2011, and made its full on-track debut at the Circuit Ricardo Tormo in Valencia, Spain, on 1 February 2011 in an interim testing livery. The definitive livery was released on 24 February, adding white, silver and red to the existing dark blue in a design directly inspired by the Rothmans livery used from 1994 to 1997.