Rubens Barrichello's spectacular accident in the Monaco Grand Prix was caused by a loose manhole cover striking his left rear wheel, his Williams team has revealed.
Barrichello was pitched into the barriers on the run up the hill out of Sainte Devote, badly damaging his Williams FW32 and leaving him facing backwards and stranded in the middle of the track.
The team conducted a detailed investigation of the wreck when the car was returned to the factory this week, and it was also alerted to the possibility that a loose manhole cover may have led to the accident.
Following that work, the team has concluded that the loose cover at Turn 2 lifted up when Barrichello ran over it and it struck his left rear wheel - causing the failure.
A statement issued by the team on Friday night said: "The car was badly damaged in the ensuing crash which ended Rubens' race. This incident has been reported to the FIA."
The Barrichello incident came shortly before a further safety car period caused by a loose drain cover at Turn 3.
The FIA will likely conduct its own investigation into the matter and could make recommendations to the Monaco Grand Prix organisers to improve the welding down of drain covers for next year's race.