Lewis Hamilton and Valtteri Bottas led the field from Max Verstappen in FP2 at Monza, confirming the Brackley squad's edge over its Red Bull rival at the Temple of Speed.
But the final rehearsal ahead of this afternoon's sprint event was disrupted by a heavy crash for Carlos Sainz in which the Spaniard's Ferrari came off the worse for wear.
With qualifying done and dusted, and aero configurations set in stone, the second practice session provided little significance to teams but was nevertheless an opportunity to add more mileage, fine tune settings and tyre knowledge for race day.
Haas' chargers Mick Schumacher and Nikita Mazepin were the first drivers roll out onto the track, with the pair followed by another group of contenders, with the lot running on various compounds.
Red Bull's Sergio Perez set the early pace while his teammate remained in his garage, as did the two Mercedes cars.
But a little over the fifteen-minute mark, a soft-shod Verstappen joined the fray and duly demoted Perez at the top of the time sheet, the Red Bull duo followed by Gasly and Hamilton who had also joined the action in the interim.
The Briton's teammate and the poleman for this afternoon's sprint race, Bottas, also put himself into gear but the Finn opted to indulge - like most of his colleagues - in a long run on the hard tyre, likely to gauge the white-walled rubber.
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As the session reached the halfway mark there was drama in the Ferrari camp, with Carlos Sainz heavily crashing in the middle of Ascari chicane. The Spaniard was uninjured but justifiably out of breath and quipped "massive crash" over the radio, with the SF21's front end bearing the brunt of the impact.
Depending on the level of damage, the misstep could signify a new monocoque for Sainz and a pitlane start this afternoon, much to the Tifosi's chagrin. It was also the second crash in two weekends for the Ferrari driver.
The subsequent red flag caused by the incident shaved a good ten minutes off the duration of the session. Hamilton, still running on the soft tyre, improved on his previous time as did Bottas, now also on the softs, as the Mercedes tandem led Verstappen by half a second.
Leclerc was also among the notable improvers, the Monegasque putting himself on the fringe of the top ten. However, the Ferrari driver warned his team that he needed to stop, but added that he couldn't explain why over the radio, a message that perhaps suggested a physical issue.
The disrupted session concluded without any changes at the front, with Mercedes and Red Bull holding the top four spots, while Alpine's Esteban Ocon rounded off the top five.
Robert Kubica was an impressive P6, just outperforming teammate Antonio Giovinazzi, with Alonso, Gasly and Norris completing the top ten.
Ahead of this afternoon's sprint race confrontation, Mercedes' edge over Red Bull appears relatively clear. But the rush into the first chicane promises to be a frantic affair, and one that could decide the outcome of the 30-minute dash.
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