F1 championship leader Charles Leclerc survived three spins at a treacherous Imola to lead the way in the only practice session for the Emilia Romagna Grand Prix ahead of qualifying.
The rain had started falling on Thursday afternoon, turning heavy overnight and into the morning, and while it had eased by the start of FP1, it naturally continued to play havoc.
Throughout the hour-long session, with all the drivers conducting as much running as possible knowing the conditions would still be prevalent for afternoon qualifying, there were multiple spins and offs across the gravel given the slippery circuit.
Leclerc was chief among the spinners, doing so on three occasions, initially at the right-left kink of the Variante Alta, then later on the run down to Acque Minerale, and finally emerging out of Tamburello.
The Monégasque, however, was still a cut above his rivals as he finished the session with a leading time of one minute 29.402, finishing almost nine-tenths of a second clear of Ferrari team-mate Carlos Sainz.
The only driver closest to the Scuderia pair was Red Bull's Max Verstappen who was 1.465s adrift of Leclerc, with the Dutchman then 1.572s clear of Kevin Magnussen in his Haas who was followed on the timesheet by team-mate Mick Schumacher, with the duo split by half-a-second.
For Lewis Hamilton, it was another problematic session in his Mercedes as the seven-time champion was left languishing in a miserable 18th, just over seven seconds back.
Hamilton initially complained he could not switch on the intermediate tyres once they could finally be run and that he lacked grip later in the session.
Team-mate George Russell was 10th but still five seconds down on Leclerc who has proven this year's F1-75 is now good in all conditions.
The opening exploratory lap from Alfa Romeo's Valtteri Bottas was a 1:43.277s so it was a mark of the 'drier' line the drivers managed to groove around the track that by the end of it the leading time was quicker by 14 seconds.
Bottas, though, ended the session in an ignominious fashion by crashing into a tyre barrier after time had expired. Despite the conditions, he was the only driver to be involved in an accident, finishing 11th quickest just behind Russell.
Behind the remarkable Haas pair, Red Bull's Sergio Perez and Fernando Alonso in his Alpine were sixth and seventh on the timesheet, both almost four seconds back.
Aston Martin's Sebastian Vettel and Yuki Tsunoda in his AlphaTauri followed next ahead of Russell, with the McLaren pair of Lando Norris and Daniel Ricciardo down in 14th and 15th.
Norris, in particular, twice found the gravel, on the second occasion temporarily bringing out a red flag late on as he appeared to be beached before managing to extricate himself and return to the garage.
Emilia Romagna Grand Prix first practice results
1. Charles Leclerc [Ferrari] 1:29.402
2. Carlos Sainz [Ferrari] +0.877
3. Max Verstappen [Red Bull] +1.465
4. Kevin Magnussen [Haas] +3.037
5. Mick Schumacher [Haas] +3.586
6. Sergio Perez [Red Bull] +3.610
7. Fernando Alonso [Alpine] +3.758
8. Sebastian Vettel [Aston Martin] +3.963
9. Yuki Tsunoda [AlphaTauri] +4.209
10. George Russell [Mercedes] +4.860
11. Valtteri Bottas [Alfa Romeo] +5.213
12. Pierre Gasly [AlphaTauri] +5.702
13. Esteban Ocon [Alpine] +6.018
14. Lando Norris [McLaren] +6.100
15. Daniel Ricciardo [McLaren] +6.223
16. Lance Stroll [Aston Martin] +6.631
17. Alex Albon [Williams] +7.059
18. Lewis Hamilton [Mercedes] +7.062
19. Zhou Guanyu [Alfa Romeo] +8.048
20. Nicholas Latifi [Williams] +10.296