Max Verstappen ended the opening day of running for the Formula 1 Saudi Arabian Grand Prix fastest in both practice sessions.
Verstappen headed team-mate Sergio Perez in Free Practice 1 before heading Fernando Alonso in the second hit out.
He ended the day 0.2s clear of the Aston Martin driver with team-mate Perez third best after qualifying simulation midway through Free Practice 2.
A key difference from the day's opening running was the sun had dropped below the horizon, dropping track temperatures by almost 15 degrees.
It saw a busy start to proceedings with 19 of 20 drivers venturing out soon after the session began – Perez remaining in the sheds.
Hard and medium compound tyres were again the preferred option.
Lewis Hamilton pinched a brake early on to run deep into Turn 1 but was able to skate through the runoff, cut through the back of the apex kerb at Turn 2, and rejoin without further incident.
As he did, Carlos Sainz went fastest with a 1:31.080s.
A mistake for Yuki Tsunoda saw the Scuderia AlphaTauri driver turn in too early, brushing the wall at Turn 7.
Perez didn't remain in the garage for long and was soon on track with a set of medium compound tyres bolted on.
After nine minutes, Alonso rose to the top of the timesheets with a 1:30.612s which left him 0.189s clear of Verstappen and Lance Stroll who'd set the third-best time.
An aggressive lap from Verstappen saw Dutchman move 0.370s clear of team-mate Perez with a 1:30.058s as times began to tumble.
The Red Bull driver then improved to a 1:29.952s to extend his advantage out to 0.4s.
Despite that, he reported a problem with his headrest left him unable to feel the car as well as he'd like.
Alonso switched to the soft compound tyres just prior to the 20-minute marker, improving only to second fastest after he ran wide at the Turn 22/23 complex.
His effort opened the gate for others to follow suit in switching focus to single-lap pace.
A push lap from Perez saw the Mexican shoot to the top of the timesheets with a 1:29.902s, less than 0.1s quicker than Verstappen who was on an out lap at the time.
Again, traffic was an issue, with Sainz and Alonso having a near miss as the Aston Martin came up to the Ferrari while on a push lap.
Having had to abort his initial qualifying simulation after encountering traffic at the end of the lap, Verstappen completed a slow lap before going for a second run on the soft tyres.
He was able to improve to 1:29.603s, leaving him 0.299s up on Perez.
Alonso split the two Red Bulls with a 1:29.811s with his qualifying simulation just after the halfway point in the 60-minute session.
At Mercedes, George Russell reported back that he was unhappy with his car, saying “we need to make some big changes.”
The Brit sat fifth fastest, 0.467s away from Verstappen's pace.
Nyck de Vries caught the eye of officials when he cut the pit entry line on his way into the lane.
He was shown a black and white flag, as Lando Norris had been in Free Practice 1.
The latter third of the session saw focus once again switch to race runs, with the timesheets remaining largely unchanged.
It left the order with Verstappen fastest, Red Bull again looking in a comfortable position despite Aston Martin looking to have moved closer.
The reality is likely to be a result of fuel loads and track/traffic management.
Aston Martin looks to enjoy a similar pace to what it had in Bahrain; somewhere behind Red Bull but in the mix with Ferrari.
Alpine showed strongly, with Esteban Ocon fourth best on single run pace and Pierre Gasly in sixth.
The Enstone operation flew under the radar to an extent though suggested it would slot in between the leading three teams and potentially ahead of Mercedes.
Oscar Piastri ended the day with the 19th best time, while Lando Norris was 12th best, just over a second slower than Verstappen.
Free Practice 3 follows on Saturday, starting at 16:30 local time (00:30 AEDT Sunday) ahead of qualifying at 20:00.