The Canadian, who is fighting for a new contract to stay on the grid with Team Grove, surprisingly rose to the top in the dying moments of a slippery FP3 to beat second practice leader Leclerc.
A downpour in the hour before FP3, which helped flood the paddock and caused a few motorhomes to flee, created a cautious start to Saturday’s one-hour session.
The rain tire was the choice of the peloton, with Leclerc taking the blue-walled rubber to 1m46.044s initially before Sainz found half a second to sit tentatively at the front of the pack.
Then two-time champion Alonso ventured onto intermediates, requiring numerous corrections throughout the lap and he was eventually 5.8 seconds off the pace as the crossover point had not yet arrived.
Charles Leclerc, Ferrari F1-75
Photo by: Glenn Dunbar / Motorsport pictures
The integral rains continued to be the optimal tire for the conditions, as Leclerc needed just 10 minutes to post his 1m43.364s effort that would take him to the top of the standings for most of the session.
This gave him a cushion of 1.25s over Sainz before heavy rain arrived – without any Red Bull or mercedes cars taken out of the garage.
Stroll would topple Alonso before a series of errors at Turn 4 – Zhou, Pierre Gasly, Nicholas Latifi and Alex Albon fighting understeer and oversteer to demand clearance on the outside of the left-hander at medium speed.
With deteriorating conditions, Lewis Hamilton and Leclerc left the cockpit completely to leave only Mick Schumacher on the track after 22 minutes.
Six minutes later, the track was relatively busy as the standing water began to clear – this allowed the Haas cars to climb to 3-4 and the forecast said there would be no more rain as visibility was improving.
That wouldn’t stop Gasly from pulling out a yellow flag soon after when he cut the inside kerb at Turn 7 to turn, which preceded Russell by continuing straight into Turn 12.
Alex Albon, Williams FW44
Photo by: Zak Mauger / Motorsport pictures
It came as Mercedes struggled to generate tire temperatures at the rear axle, prompting a nod from Lewis Hamilton.
As Alonso moved back to second, posting a 1m43.570s, as he persisted with the intermediates, Aston Martin driver Vettel then signaled a red flag with nine minutes to go.
The AMR22 broke away from the retired four-time world champion on the left-hander of Turn 10, introducing him to a career through gravel and the biff side into the barrier.
The session would resume six minutes later, with Verstappen finally completing a representative lap as the checkered flag came out to move fastest, with the RB18 clocking a time of 1m43.205s.
He was then immediately knocked down the line by Leclerc, the Ferrari driver – who moments before took a 360 degree spin from Turn 3 – improving to 1m42.141s.
With Albon in what would be third in the final moment, all eyes were on Latifi in the Williams.
He had held the best time of all in the first sector of the updated FW44.
And as the last driver to cross the line, the Canadian had assembled a sequence of micro purple sectors to cross the line in 1m41.480s to find 0.6s on Leclerc.
This happened despite having to go around a Alpha Tauri at turn 1 and lots of fixes.
Verstappen, as a result, would be relegated to fourth place ahead of Russell and Alonso.
Meanwhile, FP1 topper Sainz would be relegated to seventh on Norris and Vettel’s final attempt.
Ricciardo and Stroll led Zhou, while Tsunoda finished a messy session for AlphaTauri in 17th over Bottas, Gasly and Sergio Perez – the Red Bull with the fewest laps with only 21 combined.