France's Johann Zarco claimed the fastest time in practice on Friday ahead of Sunday's final MotoGP race of the season in Portugal.
Zarco on the Avintia Ducati was pushed hard by Spaniard Maverick Vinales at Portimao but was just slightly quicker with a time of 1min 39.417sec.
Vinales will happy with an encouraging showing though as he looks to win a six-way battle for second place in the standings, after his compatriot Joan Mir secured the World Championship last weekend in Valencia.
Mir posted the sixth fastest practice time as the Suzuki rider looks to add a final flourish to his maiden title, which made him the first new MotoGP champion since Marc Marquez in 2013.
But second place remains up for grabs this weekend while a new race winner would make it 10 for the season, beating the all-time record.
Aleix Espargaro is among those hoping to claim that honour and he completed the top three in practice, ahead of Fabio Quartararo and KTM's Brad Binder, in fourth and fifth respectively.
Andrea Dovizioso and Pol Espargaro, who are also in contention for the runner-up spot, came after Mir, with Australian Jack Miller and Franco Morbidelli taking the last Q2 spots in ninth and tenth.
Miguel Oliveira made the most of home comforts to clock the fastest time in the morning session but faded in the afternoon and ended up sitting 13th.
Nine-time champion Valentino Rossi, who is making his last appearance for Yamaha's factory team before leaving for the satellite Petronas team in 2021, suffered a fall and finished 21st.
Combined fastest times from Friday's practice sessions at the Portugal MotoGP:
1. Johann Zarco (FRA/Ducati) 1:39.417, 2. Maverick Vinales (ESP/Yamaha) at 0.119sec, 3. Aleix Espargaro (ESP/Aprilia) 0.228, 4. Fabio Quartararo (FRA/Yamaha) 0.275, 5. Brad Binder (RSA/KTM) 0.280, 6. Joan Mir (ESP/Suzuki) 0.315, 7. Andrea Dovizioso (ITA/Ducati) 0.324, 8. Pol Espargaro (ESP/KTM) 0.366, 9. Jack Miller (AUS/Ducati-Pramac) 0.403, 10. Franco Morbidelli (ITA/Yamaha) 0.471