It meant teams adopted slightly different run plans to usual as they got to grips with the high-speed circuit.
The top five – which was completed by Mercedes’ George Russell – all set their best times on the Hard tyre, with sixth-placed Fernando Alonso the fastest driver on Mediums, and Lando Norris in seventh the quickest driver on Softs.
The top 10 was rounded out by Mercedes’ Lewis Hamilton, AlphaTauri’s Yuki Tsunoda and Williams’ Alexander Albon.
Liam Lawson began his first full race weekend for AlphaTauri in 13th spot, behind fellow rookies Oscar Piastri and Logan Sargeant.
In a relatively quiet session Alfa Romeo had the biggest issues as Valtteri Bottas and Zhou Guanyu were initially unable to leave the garage amid suspected anti-stall issues.
Both drivers than complained about bottoming along Monza’s lengthy straights and wound up 15th and 20th respectively.
Aston Martin handed running to reserve driver and reigning Formula 2 champion Felipe Drugovich.
It marked Drugovich’s first time in the AMR23 since pre-season testing, when he replaced the injured Lance Stroll, and finished 18th overall.