A rain soaked FP3 session allowed Red Bull's Max Verstappen to achieve a clean sweep in free practice at Istanbul Park.
But the treacherous conditions limited running, with several drivers, including Lewis Hamilton, not setting a time while others ventured out only to find themselves quickly facing the wrong way, overall conditions that were a prelude to a very uncertain afternoon qualifying session.
Saturday at Istanbul dawned cold and overcast, but by the time the pitlane sprung into life, a drizzle of rain had set in, an element that would only accentuate the track's grip issues.
A wet FP3 session would normally compel drivers to refrain from any significant running, but with conditions expected to extend into the afternoon, cautiously testing the waters would prove useful.
Racing Point's Sergio Perez was offered the award for first spin of the day, while Ferrari's Leclerc navigated his way to the top of the time sheet in the early part of the session.
A few other drivers found themselves facing the wrong way as the rain showed no signs of letting up.
A run on the intermediate tyre propelled Max Verstappen to the top, while a spin by Leclerc at Turn 3 brought the Scuderia driver perilously close to the barriers.
As the rain got heavier, the traffic on the track dwindled, with few drivers seeing the point of risking damage just hours ahead of qualifying.
AlphaTauri and Alfa Romeo's contenders pressed on however, until Antonio Giovinazzi pushed his luck, spun into the gravel and nearly took the front end off his C39.
Lewis Hamilton indulged in a few exploratory laps before he radioed in to tell his team what everyone already knew: "There's just no grip here, shocking!" quipped the Mercedes driver.
The washed-out and unrepresentative session thus concluded with - for the record - Verstappen completing a clean sweep in free practice.
The only positive takeaway from the soggy morning session was that it will have added another layer of uncertainty for this afternoon's qualifying.