Fernando Alonso's morning best of 1m22.444s was comfortably the fastest time of a rain-hit first day of testing at Mugello on Tuesday.
In contrast to the morning, when a wet circuit had slowly dried, the afternoon started wet following lunchtime showers and only worsened as torrential rain settled in, severely disrupting team's test programmes and the anticipated phasing in of new upgrades.
Conditions became so bad that the circuit at one stage had to be closed, as the emergency helicopter could not take off safely due to the low light.
As a result, several teams decided to skip the session altogether and save tyres for the second and third days of running, choosing as they must from the 100 sets of Pirelli rubber they are assigned for tests at the start of the year.
McLaren's Gary Paffett and Mercedes's Nico Rosberg - taking over from Oliver Turvey and Nico Rosberg respectively - were two of the few who did venture out. Paffett managed just four laps, while Schumacher completed five but did not set a time.
Schumacher's stable-mate Nico Rosberg finished with the highest number of laps completed of any driver, a relatively paltry 49.
The dwindling contingent of fans who braved the weather and stayed until the chequered flag were rewarded when Fernando Alonso rejoined the fray in the final hour, although the Spaniard rarely completed a flying lap as he focussed instead on practice starts from the pitlane.
Better weather is predicted for the second day of running on Wednesday, when a raft of driver changes will take place - among them Felipe Massa taking over at Ferrari and Sebastian Vettel taking charge of the afternoon running for Red Bull.
Pos Driver Team Time 1. Fernando Alonso Ferrari 1m22.444s 2. Mark Webber Red Bull-Renault 1m23.648s + 1.204s 3. Jean-Eric Vergne Toro Rosso-Ferrari 1m23.891s + 1.447s 4. Jerome d'Ambrosio Lotus-Renault 1m24.048s + 1.604s 5. Nico Rosberg Mercedes 1m24.100s + 1.656s 6. Kamui Kobayashi Sauber-Ferrari 1m24.736s + 2.292s 7. Oliver Turvey McLaren-Mercedes 1m25.303s + 2.859s 8. Jules Bianchi Force India-Mercedes 1m25.475s + 3.031s 9. Rodolfo Gonzalez Caterham-Renault 1m27.197s + 4.753s 10. Charles Pic Marussia-Cosworth 1m27.359s + 4.915s 11. Valtteri Bottas Williams-Renault 1m29.179s + 6.735s 12. Gary Paffett McLaren-Mercedes 1m50.898s + 28.454s 13. Michael Schumacher Mercedes No time All Timing Unofficial
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