Verstappen set the benchmark pace on the medium rubber in the early stages before improving his switch to the softs, edging Leclerc by 0.347 seconds in a scrappy session for the Ferraris.
To williamsappendicitis forced Albon to the sidelines and former Formula E champion de Vries in his seat for the rest of the Italian GP.
De Vries, who drove for Aston Martin in FP1 instead of Sebastian Vetteltook the Monza circuit ahead of his race debut on Sunday with 36 minutes remaining in the one-hour session and immediately took 18th place on medium tyres.
A slow start to the final Monza weekend practice meant only six drivers had recorded lap times after the first 10 minutes of racing.
red bulls Sergio Perez set the first benchmark with a 1m23.448s on medium rubber.
It then went to 1m22.611s and 1m22.148s, with Alfa Romeo Valtteri Bottas about two seconds behind in second after a first run on soft rubber.
Perez’s Red Bull teammate Verstappen was forced to abort his first flying lap on medium tires just over 10 minutes into the session when he encountered slow traffic in the form of Mercedes. george russell.
Bottas was forced through the first chicane after puncturing his soft tires trying to avoid Perez, with the stewards placing the incident under investigation before opting to summon the Spaniard after FP3.
Sainz’s session was complicated by another complication when he was told to box soon after with a suspected fuel system problem, but he was able to get back on track with about half a remaining hour.
After his first lap time attack was hampered by Russell, Verstappen took the lead with a 1m21.872s on medium tires just under 20 minutes into the session as the Ferrari of Leclerc moved up to second place on the same compound.
Verstappen’s position remained intact when Sainz moved up to second on soft compound with 15 minutes to go before the Red Bull driver clocked 1m21.252s in his qualifying simulation on the redwall tyre.
It would be the fastest lap of the weekend so far ahead of qualifying, with Leclerc holding second ahead of Perez.
Leclerc completed his fast first lap on the soft tires towards the end of FP3, making the most of the compound for his second attempt.
De Vries improved to 1m22.869s, although he suffered an off-track moment coming out of the first Lesmo with around half an hour of the session still to go.
McLaren’s Daniel Ricardo directed Bottas, Aston Martin’s Sebastian Vettel, Haas duo Kevin Magnussen and Mick Schumacher – who was held up in his garage until the final 10 minutes with a clutch problem – and Spear Stroll in the second Aston.