Less than three tenths covered the Mercedes driver Bottas and McLarens driver Sainz, with second McLaren of Lando Norris a tenth further behind.
Bottas's flying lap of 1: 20.089 was one of the fastest we have seen so far by Mercedes a clear almost seven tenths ahead of his team-mate Lewis Hamilton who ended the session fifth quickest behind Renaults Daniel Ricciardo
Happiness at Renault garage didn't last long as Ricciardo had to pull over a ten minutes earlier due to team saying: fuel pump issues, causing a red flag.
Ricciardo 'pace hasn't gone unnoticed as he was lapping significantly faster through the Qualifying and considerably faster than Red Bull Racing- the closest rivals of Mercedes Amg F1 so far this season.
Max Verstappen whose lap came on medium tires (the only driver to do so) ended the session sixth fastest ahead of teammate Alex Albon and Renault's newely signed Esteban Ocon.
Racing Point F1's driver rounded off the top ten ahead last year's Italian GP winner Charles Leclerc.
Alpha Tuaris driver ended the session P12 and P13 the last drivers to be with in one second of Bottas with Kvayt being ahead of Gasly.
Ferrari powered Haas drive Grosjean finished ahead of factory Ferrari's Sebastian Vettel with Kevin Magnussen and Kimi Raikkonen behind at P16 and P17 respectively.
Williams drivers George Russel being ahead of Latifi finished P18 and P19 ahead of other Alfa Romeo and dead last Antonio Giovinazzi.
CLASSIFICATION OF FREE PRACTICE 3: