Sao Paulo: Triple world champion Lewis Hamilton gave Mercedes team mate Nico Rosberg a reminder on Friday that he will not hand over his Formula One title without a fight in Sunday's Brazilian Grand Prix.
The Briton, 19 points behind the German with two races remaining, was fastest in opening practice at Interlagos with a lap of one minute 11.895 seconds on soft compound tyres while Rosberg was third and 0.230 off the pace.
Red Bull's Dutch teenager Max Verstappen was second on a sunny morning in Sao Paulo, a mere 0.096 slower than Hamilton, and looking like he could make life difficult for the two title contenders.
Rosberg, who is unlikely to lose too much sleep over the Friday times, can clinch his first championship title if he wins on Sunday, wherever Hamilton finishes.
On paper he has a good chance, having won the last two Brazilian Grands Prix from pole position, but Hamilton -- wearing an Ayrton Senna themed helmet this weekend -- has the momentum after victories in Texas and Mexico.
The weather at Interlagos can change from sunshine to torrential rain in a matter of minutes and the race has a history of surprises and drama, meaning there is still everything to play for.
Were Hamilton to win and Rosberg fail to score, the Briton would lead the championship to an Abu Dhabi finale that could crown either of the Mercedes drivers.
Australian Daniel Ricciardo was fourth fastest for Red Bull who have improved steadily this season and are the only team other than Mercedes to have won races.
Finland's Valtteri Bottas was fifth fastest for Williams with Mexican Sergio Perez and Germany's Nico Hulkenberg sixth and seventh for Force India.
Brazilian Felipe Massa, a double winner at Interlagos who is making his home farewell this weekend before retirement, was eighth on the timesheets.
Ferrari's Sebastian Vettel was ninth, on the slower medium tyres, after spinning off in the closing minutes -- his comments over the radio swiftly bleeped out on the television feed.
The German was warned after an expletive-laden outburst at the previous race in Mexico.
Russian reserve Sergey Sirotkin took Kevin Magnussen's place at Renault for the morning session while Monegasque driver Charles Leclerc was given a practice run in Mexican Esteban Gutierrez's Haas.