Charles Leclerc raised home hopes of an Italian Grand Prix win after spearheading a Ferrari one-two first practice in Monza and with Max Verstappen facing a grid penalty.
Around the famed 'temple of speed', Leclerc posted a time of one minute 22.410secs to finish 0.077s clear of Scuderia team-mate Carlos Sainz, who blotted his copybook late on with a late off over gravel and grass but with no damage to his SF-75.
Whilst Leclerc can head into qualifying safe in the knowledge he will be vying for pole position, Sainz is one of the many drivers set to be hit with penalties.
Red Bull's reigning F1 champion Verstappen, who has a 109-point cushion ahead of Leclerc and team-mate Sergio Perez, will serve a five-place penalty for the latest change of the internal combustion engine in his RB18.
Verstappen had to settle for only fifth on the timesheet at the end of FP1, 0.430s adrift of Leclerc, albeit he would likely have been far closer but for being baulked by McLaren's Lando Norris on his best lap during the session.
The Dutchman had posted the fastest first sector and seemed poised to challenge Leclerc for opening-session honours before encountering Norris late in the lap, to which he exclaimed over the team radio "Unbelievable!"
Mercedes duo George Russell and Lewis Hamilton, who along with Sainz and Yuki Tsunoda in his AlphaTauri will all be sent to the back of the grid due to penalties, were third and fourth on the timesheet.
Mercedes has suggested the low-downforce nature of Monza will not suit its W13 but the British duo at least suggested they will not face the extreme issues encountered at the Belgian Grand Prix a fortnight ago.
Russell finished 0.279s off the pace, with Hamilton a further 0.142s further back.
The Alpines of Esteban Ocon and Fernando Alonso were separated by just 0.024s, with the Frenchman having the edge over the Spanish driver, albeit with both seven-tenths of a second down on Leclerc.
Tsunoda and Alfa Romeo's Valtteri Bottas, another driver who will sever PU penalties, were eighth and ninth on the timesheet, followed by McLaren's Daniel Ricciardo, who was 1.101s down.
As for the currently out-of-sorts Perez, who has a 10-place penalty of his own for an engine change, was a lowly 14th, 1.251s behind Leclerc.
Williams' Alex Albon, Zhou Guanyu in his Alfa Romeo and AlphaTauri's Pierre Gasly were all ahead of Perez.
On his first outing in F1 since leaving the sport at the end of last season, Antonio Giovinazzi was 18th for Haas, followed by Nyck de Vries for Aston Martin, 1.907s and 2.321s adrift respectively.
It was De Vries' third appearance in an FP1 session this year, all for different teams after previously appearing for Mercedes and Williams.
Williams' Nicholas Latifi again brought up the rear, 2.531s behind.
Italian Grand Prix first practice results
1. Charles Leclerc [Ferrari] 1:22.410secs
2. Carlos Sainz [Ferrari] +0.077s
3. George Russell [Mercedes] +0.279s
4. Lewis Hamilton [Mercedes] +0.421s
5. Max Verstappen [Red Bull] +0.430s
6. Esteban Ocon [Alpine] +0.665s
7. Fernando Alonso [Alpine] +0.689s
8. Yuki Tsunoda [AlphaTauri] +0.850s
9. Valtteri Bottas [Alfa Romeo] +0.984s
10. Daniel Ricciardo [McLaren] +1.101s
11. Alexander Albon [Williams] +1.119s
12. Zhou Guanyu [Alfa Romeo] +1.160s
13. Pierre Gasly [AlphaTauri] +1.230s
14. Sergio Perez [Red Bull] +1.251s
15. Lance Stroll [Aston Martin] +1.278s
16. Lando Norris [McLaren] +1.446s
17. Kevin Magnussen [Haas] +1.596s
18. Antonio Giovinazzi [Haas] +1.907s
19. Nyck de Vries [Aston Martin] +2.321s
20. Nicholas Latifi [Williams] +2.531s