Charles Leclerc gave Ferrari's hopes of overturning McLaren's 24-point advantage in the Formula 1 constructors' championship a boost with a commanding performance in the Qatar Grand Prix's sole practice session.
Ferrari had been playing down expectations coming into the weekend, with the high-speed nature of the Lusail track expected to suit its title rival - and potentially Mercedes, too - more.
"On paper [this is] the biggest challenge that we're going to face since we introduced these upgrades to the car that have made us perform better," said Ferrari driver Carlos Sainz on Thursday.
"Just quickly if you look at Mexico sector two, Austin sector one, Vegas sector one, whenever there's been high-speed corners in a sector - out of the top four cars, we've never been fast. If you join the fact that this track is smooth, it's cold, and it's only those kind of corners, then on paper we should struggle."
Yet Ferrari was already 1-2 with Leclerc and Sainz before the late-session qualifying simulations in the hour-long practice, and Leclerc raised the bar with both his late flying laps.
His final 1m21.953s put him 0.425 seconds clear of second-placed Lando Norris's McLaren.
Oscar Piastri ran wide onto the gravel on his last flying lap and was third ahead of Sainz, who'd been nearly eight tenths adrift of team-mate Leclerc on their first qualifying simulations but at least got the gap down to 0.582s on his next attempt.
Red Bull retains a remote hope of hanging on its constructors' title but the evidence from practice is not promising - champion driver Max Verstappen down in 11th and Sergio Perez even further back in 18th, notching up more radio criticism from potential 2025 replacement Liam Lawson along the way after the RB came across the slower Red Bull on a quick lap.
Having dominated in Las Vegas last week, Mercedes was a more muted eighth and 10th with George Russell and Lewis Hamilton in this session.
There were some attention-grabbing laps from underdogs during the hour.
Just as Qatar's investment in what will become Audi was being announced, Valtteri Bottas put that team's current Sauber incarnation a shock sixth right at the end of the session.
That put him between fellow surprise stars Yuki Tsunoda (RB) and Lance Stroll (Aston Martin), while Alex Albon was ninth for Williams.
Pierre Gasly's eventual 15th for Alpine is also potentially deceptive - he didn't take soft tyres for the final laps like almost everyone else, but prior to that had spent much of the session in and around the top three.
Teams will go straight into sprint qualifying under the floodlights later today.
