SAO PAULO - Triple Formula One world champion Lewis Hamilton has hinted that a change of tyre pressures since the Singapore Grand Prix may have contributed to the end of his qualifying dominance and team-mate Nico Rosberg's late-season resurgence.
Rosberg won the Brazilian Formula One Grand Prix for the second year in a row on Sunday to seal his place as runner-up in the drivers' championship, also for the second year running .
Hamilton, who has now failed in nine attempts to win in Brazil, finished 7.756 seconds behind for Mercedes' 11th one-two in 18 races so far this season.
Ferrari's Sebastian Vettel was third for his 79th podium finish.
"From Singapore onwards, there's been a change to the car - but whether or not that's made a difference, I don't know really," the Briton, who clinched the title in Texas last month, told reporters.
"We'll have to see. But it has changed since Singapore."
Hamilton has not been on pole position since the Italian Grand Prix at Monza in September, with Vettel taking the top slot in Singapore and Rosberg the following five.
At that same Italian race won by Hamilton, Mercedes faced a stewards' inquiry after their cars were found to have tyre pressures below the minimum specified by Pirelli after high-speed blow-outs at the previous race in Belgium.
With some rivals calling for the champion to be disqualified while Rosberg failed to finish, the stewards ruled Mercedes had followed the specified procedures and decided to take no further action.
They did, however, call for clear guidance for future measurements.
Rosberg was more sceptical when asked if the change in pressures from Italy onwards had made a difference. "I don't think so. I think I've just raised my game. That's it," said the German after controlling the race from pole to chequered flag.