Lando Norris has outscored his teammate at each of the last five race weekends.
Lando Norris edged out team-mate and championship contender the Australian for the top spot in the closing stages of the practice session at the Brazilian Grand Prix.
Norris, who seized the title advantage from Piastri by just one point after his victory in the Mexican Grand Prix two weeks ago, outpaced the Australian by 0.023 seconds.
Until that point, Piastri had been the quickest of the McLaren pair throughout the hour before the sprint shootout due at 18:30 GMT.
Max Verstappen, the other racer in the championship fight, sitting 36 points behind behind Norris, finished in P17 as his Red Bull team followed a alternative strategy.
His teammate the Japanese driver was the sole competitor to have an incident, albeit lightly, when he rotated at Turn Four during the early running.
Tsunoda lost control over the track edges before spinning across the gravel trap, and was lucky to get away with just a slight brush of the fence.
Ferrari's the seven-time champion also spun, at the final moments of the session, spinning around through the fast downhill Mergulho turn approaching the last turn on to the main straight.
The seven-time champion finished practice in 19th place, just behind team-mate the Monegasque driver.
Norris and Piastri were far ahead of the other competitors, with Nico Hulkenberg's car P3, 0.619 seconds behind Piastri's pace.
The Aston Martin of Fernando Alonso was fourth quickest, with the Sauber of Bortoleto fifth from Mercedes' George Russell and the Alpine of Pierre Gasly and the Williams of Sainz.