Max Verstappen demonstrated Red Bull's supreme pace ahead of the Italian Grand Prix with a blistering final practice performance.
The championship leader set a lap time of one minute 21.252secs to finish 0.0353s faster than Ferrari's Charles Leclerc. at Monza.
But the Dutchman will not be in contention for pole position given his overhanging engine penalty - though Verstappen could still win qualifying and start as high as third on the grid.
The start of the session was typical of FP3 with very little track action - Sergio Perez completing much of the early running.
But when cars did emerge from the garage, it was Verstappen who was quickest on mediums, albeit just 0.072s faster than Leclerc.
When the qualifying simulations began, cars clambered for track position to pick up the all-important slipstream despite predictions the effect would be less effective with F1's new regulations.
Verstappen lay down the marker to finish ahead of likely pole-sitter Leclerc, who made an error at the de la Roggia chicane on his first attempt at a flying lap on the softs.
Perez finished the hour of running third but will also take a penalty after qualifying, as will fourth-placed Carlos Sainz.
The Spaniard has also been summoned to the stewards for driving unnecessarily slowly with Valtteri Bottas almost wiping the Sainz out at the Rettifilo chicane.
Fernando Alonso continued Alpine's fine form with the fifth quickest time, which could become a front-row berth come Sunday.
Lando Norris was sixth for McLaren ahead of George Russell's Mercedes and Yuki Tsunoda for AlphaTauri.
Esteban Ocon finished ninth but became one of three people added to the penalties list having taken on a new ICE for the session - the number of drivers to take a drop increased to nine.
Lewis Hamilton finished tenth ahead of his back-of-the-grid penalty.
It was announced before the session that Nyck de Vries would be making his F1 debut in place of Alex Albon at Williams with the Thai-British driver sidelined with appendicitis.
Called in at short notice, the Dutchman missed almost half of the session as the Williams mechanics made changes to the car to accommodate its new driver before sending him out on medium tyres.
Despite an off at the first Lesmo on his second flying lap, de Vries soon settled into a rhythm to add to the knowledge gained from his FP1 running with Aston Martin on Friday and eventually finished just a tenth down on team-mate Nicholas Latifi.
Penalties for both Haas' will add to their difficulties, with Mick Schumacher confined to the garage for the first 50 minutes of running with a clutch issue during fire-up for the session.
Italian Grand Prix third practice results
1. Max Verstappen [Red Bull] 1:21.252
2. Charles Leclerc [Ferrari] +0.347s
3. Sergio Perez [Red Bull] +0.596s
4. Carlos Sainz [Ferrari] +0.645s
5. Fernando Alonso [Alpine] +1.054s
6. Lando Norris [McLaren] +1.067s
7. George Russell [Mercedes] +1.105s
8. Yuki Tsunoda [AlphaTauri] +1.178s
9. Esteban Ocon [Alpine] +1.254s
10. Lewis Hamilton [Mercedes] +1.315s
11. Zhou Guanyu [Alfa Romeo] +1.405s
12. Pierre Gasly [AlphaTauri] +1.503s
13. Nicholas Latifi [Williams] +1.524s
14. Nyck de Vries [Williams] +1.617s
15. Daniel Ricciardo [McLaren] +1.619s
16. Valtteri Bottas [Alfa Romeo] +1.698s
17. Sebastian Vettel [Aston Martin] +1.852s
18. Kevin Magnussen [Haas] +1.951s
19. Mick Schumacher [Haas] +2.140s
20. Lance Stroll [Aston Martin] +2.487s