Max Verstappen headed a Red Bull one-two in opening practice for the Formula 1 Saudi Arabian Grand Prix.
The Dutchman was comfortably fastest at the end of the hour-long session, finishing almost half-a-second quicker than team-mate Sergio Perez.
Aston Martin backed up its Bahrain pace with Fernando Alonso third and Lance Stroll fourth.
A busy start saw a mixture of medium and hard compound tyres in use, with Perez the odd man out on a set of softs in the early minutes.
That saw the Mexican go fastest with a 1:32.969s to sit 1.4s clear of Lando Norris, who was next best on a set of hard compound tyres.
Verstappen had initially remained in the garage but emerged after six minutes, also on a set of soft rubber.
Having set his initial time, Perez returned to the pits as both Ferrari drivers climbed up the order to sit second and third – Charles Leclerc ahead of Carlos Sainz.
The former was just 0.1s off the outright pace and 0.3s away from the top of the timesheets.
At the 10-minute marker, Lewis Hamilton emerged fastest with a 1:32.665s.
The Mercedes driver managed that on a set of hard compound tyres, with Alonso on the softs slotting in second.
Perez had returned to the circuit, again on the soft compound to bounce back to the top of the timesheets with a 1:31.486s.
He was faster than anyone through all three sectors, leaving him over a second faster than Alex Albon, who had improved to second.
Traffic was proving an issue with those on slow laps often baulking those pushing on.
That came despite the walls being moved back in a number of corners to open the sightlines.
With 15 minutes run, Alonso shot to the top of the timesheets with a 1:31.262s to head Perez and Leclerc.
Though he had been out on track for a reconnaissance tour, Verstappen remained the only driver who had not set a lap time.
Track conditions were clearly improving, evidenced by Perez returning to the top with a 1:30.592s – almost 2.5s faster than his initial lap earlier in the session.
Part of that was a result of the time of day, with the sun beginning to set to offer more representative conditions for the weekend's meaningful sessions.
After 20 minutes, Verstappen headed back out and immediately went third fastest on a 1:31.564s behind Perez and Alonso.
The order at the top then reversed when the Spaniard improved to 1:30.509s, a lap 0.083s quicker than the Red Bull.
On his second timed lap, Verstappen went fastest by 0.015s with a scrappy effort which saw him miss the apex at the final corner.
The Dutchman complained of understeer, especially through the newly tightened Turn 22.
He went faster nonetheless, rising to a 1:30.062s to pull 0.447s clear of Alonso in second fastest before improving again to log a 1:29.815s.
It was a lap that came despite going slower in the final third of the lap as he sat almost 0.7s clear of the pack.
At Ferrari, both drivers sport new power units for this weekend, a precautionary move according to the team following a disappointing Bahrain Grand Prix which ended in retirement for Leclerc.
Inside the final 20 minutes, the bulk of the field had moved onto the soft compound tyres with the exception of the two Alpines, who had the medium tyres fitted.
Stroll had a near miss when he came across two slow-moving cars through the Turn 9/Turn 10 complex.
It forced the Aston Martin driver to cut across the inside of Turn 11 in avoidance.
Though most had swapped to the soft compound rubber, few were improving their times.
There were a smattering of personal best microsectors, most notably by Verstappen who managed a 1:29.790s to improve by less than 0.1s with 10 minutes remaining.
The Bahrain race winner wasn't done there, improving again to a 1:29.662s to reaffirm himself at the top of the timesheets before ending the session with a 1:29.617s.
It was a time that was over a second faster than the same session a year ago, despite Turn 22 having been modified and, theoretically, slower.
Indeed, that proved a hot spot for drivers, with most having a moment at the reprofiled left-hander.
Hamilton, Stroll, Oscar Piastri, Pierre Gasly, and a raft of others all found themselves running wide and having to cut across the apex of Turn 23.
It was otherwise an uneventful session, Verstappen heading a Red Bull one-two with Alonso third and Stroll fourth.
The Noah's Ark order continued with George Russell fifth and Hamilton sixth before that pattern broke down.
Norris was 20th and slowest, 2.4s away from Verstappen's best, while McLaren team-mate Piastri was 0.6s faster to sit 14th.
A second hour of practice follows at 20:00 local time (04:00 AEDT).
Results: Formula 1 Saudi Arabian Grand Prix, Free Practice 1
|Nyck de Vries
|Alfa Romeo Sauber
|Alfa Romeo Sauber