Fernando Alonso topped a soaking-wet first practice session at the Japanese Grand Prix that ended with a heavy Mick Schumacher crash at the esses.
Suzuka had been drenched by showers from early in the morning, and less than half the field completed more than 10 laps in the sopping 60-minute session.
Kevin Magnussen was the first out after five minutes along with local favorite Yuki Tsunoda, but drivers were slow to brave the full-wet conditions. Only as the rain began to ease did a gaggle of cars join the circuit, in turn helping to disperse the worst of the standing water.
The Ferrari drivers led the way in the worst of the conditions, with Carlos Sainz ahead of Charles Leclerc after the Spaniard reported a strange sound emanating from his power unit.
Nicholas Latifi was the first to fall foul of the tricky conditions, locking up at the hairpin and running into the gravel.
It took more than half an hour of slow track action before the track was dry enough for intermediate tires, with Valtteri Bottas, Max Verstappen and Esteban Ocon the first to sample the green-walled rubber.
Verstappen shot to the top of the order, but it was a short-lived elevation, with the times tumbling as drivers made the switch to the faster compound.
Esteban Ocon was the first to usurp him, followed by Leclerc and Sainz — who survived excursions at Degner and Spoon respectively — before Fernando Alonso logged the benchmark time of 1m42.248s on his seventh lap of the day with a little over 15 minutes to go.
With the rain intensifying again, most cars retired to pit lane, leaving Alonso ahead of the Ferrari pair and his Alpine teammate at the top of the standings.
Valtteri Bottas ventured back out late but was lucky to avoid an enormous accident running wide at 130R.
The session was effectively done when several drivers returned to the track in the final minutes to practice their starts on the grid after the checkered flag. Mick Schumacher was among them, but after practicing his launch he suddenly lost control through the rapid left-handed Dunlop curve at turn 7.
The German’s Haas car aquaplaned suddenly and freed itself from his control, spinning backwards across the track and wiping off its front-right corner against the barrier.