Verstappen’s time came out of sequence with the bulk of the pack, set in the final six minutes of the opening hour.
He headed Charles Leclerc, Lando Norris, and Carlos Sainz in a session that was promising for Ferrari.
Meanwhile Kimi Antonelli found the wall at the Parabolica just 10 minutes into the session to curtail his outing.
All 10 teams sport updates this weekend, some more than others – Ferrari’s the most significant.
That prompted a busy start for most drivers on a newly resurfaced Monza circuit.
There were other changes to get across too, with reprofiled kerbs and the addition of strips of gravel in key areas.
Oscar Piastri carried a sizeable aero rake on his McLaren, one of a handful to be equipped with such a rig.
The Australian was running a different program, logging laps but well off the outright pace.
Lando Norris was in a more conventional position on the timesheets though the presence of Valtteri Bottas in second after half an hour suggested the front runners had not turned up the wick.
Both McLaren drivers remained on the medium rubber longer than most, Norris only taking a set of softs inside the final 15 minutes.
Piastri too switched onto the soft tyres late, moving third best before dropping to fourth as his team-mate completed his qualifying simulation lap.
The timesheets therefore offered limited insight into the pecking order – Bottas holding on in fifth with Albon eighth at the chequered flag.
Indeed, for a long period Verstappen was well down the order – he was only 16th and a second off the pace before he completed a qualifying simulation.
The Dutchman only recorded a representative lap with six minutes remaining, a 1:21.676s to top the session, but the timing meant it wasn’t a like-for-like comparison with his rivals on an evolving track.
Antonelli’s bright start ended abruptly.
The Italian had been fastest on his first timed lap in Free Practice 1, but after 10 minutes he lost control at the Parabolica.
That saw him fire across the gravel trap and into the Tecpro barrier, triggering the red flag and ending his session.
It was an unusual off; Antonelli had turned in and reached the apex before the rear end stepped out suddenly and sent him to the scene of the accident.
The impact was high enough that the Medical Car was called for, prompting a trip to the medical centre for the 18-year-old who was unharmed.
In the garage, it made for an anxious moment for George Russell, who’d given up his car for the session, and cost the team of the ability to complete back-to-back comparisons with Lewis Hamilton in the other car.
Antonelli had the upgraded floor on his car, with Hamilton the older spec, though the team confirmed it had spares available.
Ricciardo finished the session only 12th fastest, the Australian a second off the outright pace but his best time coming on a set of medium tyres.
Even still, it proved a tenth faster than RB team-mate Yuki Tsunoda.
A second hour of practice follows, with Russell back aboard his Mercedes but with the older floor as Mercedes swaps the new parts to Hamilton to complete back-to-back testing of the new component.
Free Practice 2 begins at 01:00 AEST.