Lewis Hamilton said the task of overhauling Red Bull's Max Verstappen to win a record eighth Formula One title felt "as steep as it can be" with four races remaining and 19 points between them.
The 36-year-old Mercedes driver has five wins to his Dutch rival's nine this season, with Verstappen chasing his third in a row in Brazil this weekend.
Asked on Thursday whether he felt Sunday's Sao Paulo Grand Prix was a "must-win," the Briton replied that "every race is a must-win race."
Brazil is expected to favour the Red Bull more than Mercedes, with Verstappen the most recent winner there in 2019 and before the coronavirus pandemic forced the cancellation of last year's race.