Lando Norris has outperformed his teammate at all of the last five grands prix.
The McLaren driver just pipped fellow driver and championship contender the Australian for the fastest time in the final moments of the practice session at the Sao Paulo Grand Prix.
Norris, who seized the points lead from his teammate by one point after winning in the Mexican Grand Prix recently, outpaced the Australian by a tiny margin of 0.023secs.
Before then, Piastri had been the quickest of the McLaren pair for most of the session before the sprint shootout scheduled for the evening session.
Max Verstappen, the sole remaining contender in realistic title contention, lying 36 points behind behind Norris, was classified in 17th position as his Red Bull team opted for a alternative strategy.
His teammate the Japanese driver was the sole competitor to go off, if briefly, when he lost control at the fourth corner early in the session.
The Japanese slid over the curbs on exit before rotating through the escape zone, and was blessed to escape with just a slight brush of the wall.
Ferrari's the seven-time champion also spun, at the very end of the session, spinning around through the fast downhill corner approaching the final bend on to the main straight.
The seven-time champion wrapped up in 19th, one place behind teammate Charles Leclerc.
Norris and Piastri were significantly quicker of the remaining drivers, with the German's car in third, 0.619 seconds slower than the Australian's time.
Aston Martin's the Spanish driver was in fourth, with Sauber's Bortoleto fifth from Mercedes' Russell and the Alpine of Pierre Gasly and Williams' Carlos Sainz.