Max Verstappen completes almost three race distances on his way to posting the fastest time as pre-season testing gets underway.
Though it is early days, and the likes of Ferrari and Mercedes have yet to show their hands, the RB19's pace and reliability will surely have rivals already fearing that the Austrian team is picking up where it left off last season.
In total Verstappen completed 157 laps, just five shy of three race distances, the RB19 never missing a beat over the course of the day.
A further concern for his rivals is that the two-time world champion was the only driver on duty for the entire session, the nine other teams opting to split driving duties.
For much of the day it was business as usual as the cars got to stretch their legs for the first time. The day began with the focus on aero rakes and flo-vis before switching to longer runs and finally low fuel runs, the teams understandably more focussed on reliability than pace at this stage.
An added complication, other than having to change the cars over the break due to the driver swaps, was the change in climatic conditions as the sun set and floodlights lit the desert track.
It was in the final hour that the focus turned to pace and Fernando Alonso came within 0.029s of unseating Verstappen at the top of the timesheets.
A subsequent bid to improve saw the Spaniard make a mistake an run wide nonetheless both he and his Silverstone-based team will be pleased with the initial results.
As Lando Norris sought to improve, it was noticeable that the McLaren looked far more nervous, less 'planted' on the track than the Aston Martin, the Briton already having lost track time due to a brake issue understood to be a manufacturing fault.
The Ferraris were third and fourth, Carlos Sainz, who drove this morning, and Charles Leclerc separated by just 0.016s.
Lewis Hamilton was sixth quickest, 0.625s off the pace, but as ever his German team opted not to show its hand at this stage, though 83 laps for the Briton and 69 for his teammate suggests that reliability is good.
Furthermore, talking during the lunch break, Toto Wolff said that the W14 was not experiencing any bouncing, which is more than can be said for the Ferrari, which clearly has issues.
Williams had both drivers in the 'top ten', Alex Albon looking very impressive this morning, albeit posting his best time on the softer C4, while all the other leading times were posted on C3s.
Alfa Romeo's test got off to a much better start than last year, Guanyu Zhou finishing the day 8th quickest and teammate Valtteri Bottas 12th.
Both AlphaTauris were over 1.7s off the pace, as were the Alpines, while Kevin Magnussen was unable to match the pace of his teammate earlier.
However, though there were lock-ups and much exceeding of track limits and running over kerbs, which damaged a few floors, including Alonso's and Hulkenberg's, Felipe Drugovich's electrics issue caused the only red flag of the day and other than that there were no serious technical issues.
Verstappen, Sainz, Hamilton, Ocon, Norris, Magnussen and Tsunoda are all in action tomorrow morning before handing over to their teammates, while Zhou and Sargeant are both scheduled to do the full day.
"We had a good day," said Verstappen, "we completed a lot of laps which is what we wanted - almost three Grand Prix's worth.
"It was also a smooth day," he continued, "we barely had any issues and we could really focus on the car and try a few things. We had a lot of good running throughout the day when it was hot and sunny and also in the evening which is more representative.
"It's nice to see how the car has evolved from last year. The behaviour is a bit different because of the tyres but otherwise, we are happy. It's difficult to tell how the car will perform this season through one day of testing, the car is running well and that's the most important thing. I'll be running again tomorrow afternoon, so we'll be trying out different compounds and seeing what else we can learn before the race next week."
"Overall I am pleased," said Alonso. "As a team, we reached 100 laps in total, which is a strong start for the first day despite some minor issues that we resolved.
"We are still experimenting with lots of different things, so every lap we do is important and we learn something new about the car every time we go out. These first steps are always intriguing and so far I am enjoying this part of the winter preparation. We will use the information and learning from today to optimise things further tomorrow."
"Driving the AMR23 for the first time today was great, I really enjoyed it," added Drugovich. "I spent a few laps at the beginning of the day familiarising myself with being back behind the wheel, but I felt like I got up to speed quickly and before long I was back in a good rhythm.
"Despite a small electronics issue, we completed our run plan and gathered some valuable data for the team. I did quite a lot of aerodynamic testing, which is incredibly important with a new car, but I also got to do a few push laps towards the end of the session, which were great fun. Finally, I want to wish Lance a quick recovery and also thank the team for trusting me with this opportunity."
"A solid opening day of testing on the whole," said Tom McCullough, the team's Performance Director. "We had a few issues, which cost us some track time, but when the car was running we were able to get through our test plan.
"We will have to recover the time we lost over the next two days to ensure we maximise our learnings ahead of the race next week. The car was responding well to the changes we made and we will continue to review the data this evening ahead of Fernando's time in the car tomorrow.
"Felipe did an excellent job for us this morning with a lot procedural work to gather important aerodynamic data. He did not get quite as many laps in as we had planned due to this morning's electronics issue, but in the time he did have he got up to speed quickly and did a really good job.
"Fernando made good progress during the afternoon session and is continuing to familiarise himself with the new car, tyres and people around him. His feedback was incredibly valuable and will be hugely beneficial as we continue to learn more about the AMR23."
At Ferrari, there were three main objectives for the day: the usual aerodynamic mapping of the car, effectively correlating the data acquired on track with that seen in the wind tunnel and in digital modelling; checking all functions on the car over a greater distance than the 115 kilometres completed at the Fiorano track during the demo-drive at the launch and the following day's filming day; and for Carlos Sainz and Charles Leclerc to learn as much as possible about the new car.
Sainz drove out of the garage as soon as the pitlane light turned green and tried the C2, Prototype and C3 compound tyres. He completed 72 laps (390 kilometres) setting a best time of 1'33"253 on the C3 compound. After the lunchbreak, it was Leclerc's turn to get behind the wheel. His time in the car was a bit busier, with various set-up changes. He did 64 laps (346 kilometres) running the same compounds as his team-mate.
"Overall a positive first day," said Sainz. "Reliability was good and we could run smoothly, covering the whole run plan and gathering valuable data, which is encouraging. We progressed well with the setup during the day and we also managed to get good reads on the tyres we tested in Abu Dhabi so, overall good progress made so far and I'm looking forward to continuing tomorrow."
"We have a busy first day behind us," added Leclerc. "We completed 64 laps on my side, testing a bit of everything. Our focus was on set-up work, combined with some tyre and aero testing, as well as runs with different fuel levels. We're going to analyse our data now and I look forward to another session tomorrow."
"It was a reasonable first day," said Norris who ended the day 5th quickest. "It was good to be back on track, to get a good number of laps under my belt and to get that first feeling from the car, so I'm happy with that. It wasn't quite the smoothest of days with a few little setbacks here and there, but we got through a lot of the plan and some of the key test items, which we can learn from over the next few days as well some changes we can already start to implement.
"I'm feeling more comfortable in the car and have changed little things here and there to start to optimise a few things. As far as test days go, it was positive and I'm looking forward to going again tomorrow."
"My first morning of testing went pretty smoothly," added Piastri, "which is a good start to the season. We got through the programme we wanted to, which was great, with the focus being on getting myself back up to speed and used to the new generation of F1 cars. There is still a lot to learn and improvements to make but I think I'm getting there. It was good to get some laps on the board and everything felt pretty comfy. I'm looking forward to my next few sessions to keep improving and learning more about the car."
"A productive day which went largely to plan," said Andrea Stella. "Despite a few very minor issues, which are common at testing, we've got a lot of information and were able to complete a lot of test items. There were some short delays caused by the team wanting to reinforce the body work in some places in order to prevent a failure.
"These were preventative measures, but we thought they were useful to make so we could run safely and reliably for the remainder of the day. Overall, a positive day. We hope to continue like this for day two and three so we're ready for the first race of the season."
Check out our Thursday gallery from Bahrain, here.