Carlos Sainz has topped a second free practice session twice interrupted by red flags with Lando Norris second best.
Sergio Perez ended the session third but spun inside the final 10 minutes to prompt its second interruption after Lance Stroll had triggered the first.
While the opening session afforded little opportunity to draw accurate conclusions, traffic and the stoppages mixed up the order.
That saw Lewis Hamilton only 17th, the Mercedes driver having not banked a low-fuel, soft tyre run.
Soon after the session began, it stopped again when the red flag was thrown for Lance Stroll who'd stopped at the exit of Variante Ascari.
There was no damage to the Aston Martin, it had simply been pulled to the side of the road while with an apparent hydraulics failure – the Canadian had not been changing gears ahead of stopping the car.
After failing to get the car refired, it was eventually pushed back across the track to an opening in the barriers, a bonus as it simplified the recovery of the stricken machine.
The team subsequently clarified a fuel system issue was the cause of his stoppage, a hit for Stroll who sat out Free Practice 1 as Felipe Drugovich drove the car earlier in the day.
Once behind the barrier, the session quickly restarted, having been interrupted for seven minutes.
Again, teams approached the session differently from a tyre perspective with Red Bull on mediums with its drivers, versus the hards earlier in the day.
Traffic was an issue; Oscar Piastri found his path baulked by Lewis Hamilton before a train of cars formed on approach to the Parabolica.
It was a worrying glimpse into what Qualifying 1 could descend into as none of the drivers wanted to lead, while all wanted a tow.
Midway through the session, the soft tyres were bolted onto the cars from Maranello as they began their qualifying simulations.
Red Bull was on track doing the same thing, Max Verstappen and Sergio Perez practising using the two down the front and back straights.
Complicating matters was the fact others were on track running a similar, but not the same, programme.
As a result, there were cars trundling around while others were on hot laps, leading Verstappen to complain about traffic in the middle sector as he banked a 1:21.631s.
The Dutchman passed more than six cars from Lesmo 2 through to the Variante Ascari, his exit to the right-hander compromised.
It left him 0.091s away from Perez, who'd only gone 0.025s quicker than Sainz's earlier effort.
McLaren showed good pace with Lando Norris going fastest for a time, only for Sainz to better it as Oscar Piastri slotted in fourth best.
With nine minutes remaining, Perez spun exiting the Parabolica, the rear of the car making contact with the Armco barrier.
That drew the second red flag as the car sat perpendicular to the direction of travel, albeit some way off line.
The Mexican had understeered off earlier in the corner, bouncing through the gravel as the rear eventually overtook the front and nudged into the barrier near corner exit.
Under the stoppage the clock continued to tick down, leaving just four minutes by the time the green flag was displayed at pit exit.
That prompted a stampede out of the lane with all 18 remaining runners – Stroll's car issue was not able to be remedied during the session – heading out on track.
The chequered flag waved soon after with Sainz fastest over Norris and Perez, followed by Piastri and a somewhat frustrated Verstappen.