Lando Norris laid down an early marker by seeing off world championship rival Oscar Piastri in practice for the Sao Paulo Grand Prix.
Norris, who heads Piastri by one point with four rounds remaining, finished just 0.023 seconds clear of his team-mate at Interlagos with McLaren setting the early pace.
Max Verstappen, 36 points behind Norris in the standings, was only 17th as he failed to set a representative lap on the speedier medium tyre compound.
Norris delivered a dominant performance at the previous round in Mexico to regain top spot in the title standings and demote Piastri into second place.
Piastri had led the title race since April but saw his advantage evaporate as he struggled to find top form.
Here, the Australian looked on course to receive a timely boost prior to qualifying as he sat on top of the time sheets until he was usurped by Norris in the closing seconds.
Nico Hülkenberg took third spot for Sauber, six tenths off the pace, with Aston Martin's Fernando Alonso fourth and home favourite Gabriel Bortoleto fifth. George Russell finished sixth for Mercedes.
Lewis Hamilton enjoys strong support from the Brazilian fanbase in Sao Paulo. But they had little to cheer as Hamilton ended the first running of the weekend last but one, and also spun at the penultimate corner as the one-hour session drew to a close.
Hamilton's Ferrari team-mate Charles Leclerc was only one place better off in 18th.
