Ferrari's Charles Leclerc picked up where he left off in Belgium last weekend, posting the fastest lap in a tricky and overall damp first practice session for the Italian Grand Prix at Monza.
Conditions - which caught out many drivers and generated severakl red flags - remained damp until the ultimate minutes of running when a handful of drivers ventured out on dry tyres.
The medium-shod Leclerc edged McLaren boys Carlos Sainz and Lando Norris - running on the soft compound - by a few tenths of a second, while Mercedes Lewis Hamilton and Red Bull's Alex Albon rounded off the top five.
The heavens above Monza unleashed their wrath overnight and while the downpour had subsided at sunrise, drivers head out on to a damp track at the start of FP1 with everyone fitted with Pirelli's wet tyre.
Running wasn't expected to be very representative given the conditions, but with rain currently scheduled for Sunday, gathering a bit of data on the wet track may have proven to be a useful exercise.
Ferrari Charles Leclerc's outlap was greeted by the Tifosi with a loud roar, the Monegasque seeking to uphold his Spa momentum at the Scuderia's home race.
Few were those who ventured out onto the track for more than a single lap, but Norris eventually gave it a go and put the first timed lap on the board.
Others followed but the 19-year-old, sporting his special Valentio Rosso-themed helmet, remained on top until Toro Rosso's Dany Kvyat strung together a series of purple sectors.
The first red flag of the day came after about 30 minutes, courtesy of an off by Alfa's Kimi Raikkonen at Parabolica, the Finn lightly hitting the barrier.
Meanwhile, Carlos Sainz indulged in a spectacular but harmless 360 spin at the exit of Variante Ascari.
Minutes after the track had gone green, it was back to red following an off by Racing point's Sergio Perez, again at Ascari where the Mexican hit the barriers on the exit, ripping off a wheel and destroying his rear wing.
When the action resumed, Renault's Nico Hulkenberg went to the top but was swiftly overhauled by Verstappen who set a new benchmark of 1m35.397s.
Improvements were in order thereafter, but Pierre Gasly brought out Red Flag #3 at Variante del Rettifilo.
After a short interruption, Kvyat snatched the fastest lap from Verstappen until Leclerc posted a 1m32.007s.
Over an hour of running, Hamilton finally put a time on the board, which was just a few tenths down on Leclerc.
Mercedes had tardy start to Fp1 but quickly made up for the lack of running, with Bottas and Hamilton taking over from Leclerc.
Finally, the front-runners unwrapped a few sets of soft and medium tyres to test Monza's almost dry waters.
In the final minutes of the session, Sainz popped up to the top of the timing screens with the first sub-1m30s lap, but Leclerc would have none of it, pipping the Spaniard by 0.306s for FP1 bragging rights.
Norris ended the session third, followed by Hamilton, Red Bull's Alex Albon, Kvyat and Verstappen, while Vettel, Bottas and Gasly rounded off the top-ten.