Charles Leclerc topped the final practice session at the Singapore Grand Prix after heavy rain reduced running to less than 30 minutes.
The session officially started on time, but race control kept pit lane closed for the first 30 minutes given the circuit was waterlogged after two hours of torrential downpour.
The safety car lapped in the first 10 minutes of the suspension, after which marshals entered the track to sweep away some excess standing water.
With the rain having fully abated, pit lane opened with half an hour of the 60-minute session remaining, and a few minutes later Pierre Gasly became the first driver to brave the conditions with a set of full wet tires.
Most of the rest of the field eventually followed him out, some for only a lap or two, and after 12 minutes Gasly made himself the first among them to switch to intermediate rubber, kicking off a grid-wide move to the green compound.
Despite the treacherous conditions and bumpy circuit, the closest any driver came to having an incident was Nicholas Latifi running into the run-off area at Turn 13, for which the Canadian blamed a steering problem that prevent him from turning into the corner. His Williams teammate, Alex Albon, went off shortly afterwards before Latifi went off at Turn 5 with a significant lock-up.
Track conditions improved constantly in the final 15 minutes, and the lap times tumbled throughout.
Leclerc and Max Verstappen spent the final minutes of the hour trading fastest times until the Ferrari driver broke the deadlock with a bear of flyers to put him at the top if the order with a time of 1m57.782s.
Verstappen’s best response left him 0.526s adrift, with Carlos Sainz a second adrift in the sister Ferrari car.
Fernando Alonso was fourth after being the last to join the session along with teammate Esteban Ocon, who finished the tricky hour seventh, the teammates split by Sergio Perez and Lance Stroll.
Sebastian Vettel was eighth ahead of George Russell, who looped his car heading to the grid for a practice start after the checkered flag. Gasly wound up 13th after missing turn 18 and taking to the run-off zone.
Mick Schumacher ended the hour under investigation for being released from his pit box without all four wheels secured. His team noticed in time to stop him from leaving pit lane, meaning he could be wheeled back to his garage rather than stopping on track.
Yuki Tsunoda flirted with the barrier at Turn 14 on his way to 15th, having vented over team radio about being held up by Lewis Hamilton in the final minutes. Lando Norris followed in 16th ahead of, Albon, Alfa Romeo teammates Valtteri Bottas and Zhou Guanyu, and Latifi at the back of the pack.