World championship leader Lewis Hamilton is one of three drivers under investigation by the race stewards at the Brazilian Grand Prix for breaching the wet weather tyre rules.
McLaren's Hamilton, Honda's Jenson Button, and Super Aguri's Takuma Sato were deemed to have used two sets of wet weather tyres during the first free practice session at Interlagos, in breach of the Sporting Regulations.
Article 25.3 of the F1 Sporting Regulations states: "No driver may use more than one set of wet and one set of extreme weather tyres during P1 and P2."
The matter was brought to the race stewards' attention by FIA technical delegate Jo Bauer, and it is not clear at this stage whether or not the drivers involved will face any sanction.
All three drivers have been summoned to see the stewards individually following the end of the second practice session.