Carlos Sainz's early Williams debut came with a warning. Not in the form of setting the second-fastest time in Formula 1's post-season testing in Abu Dhabi - that counts for nothing - but how emphatically he torpedoed the notion he regards a move from Ferrari to the ninth-best team in F1 as below him.
For some, dropping out of a championship-challenging team in exceptional circumstances (in Sainz's case, Ferrari's shock signing of seven-time world champion Lewis Hamilton) and finding no room at the inn at other top teams would mean Williams was nothing more than a place to mark time, keep sharp, top up the bank balance and chase a big-team return from.
But Sainz, decked out in white overalls and keeping a low profile out of deference to current employer Ferrari on his initial Williams runs, is no such character.
Speaking after finishing second in the Abu Dhabi Grand Prix, even by the most optimistic prediction likely to be his last F1 podium until at least 2026, Sainz made emphatically clear his complete buy-in to the project.
"It's impossible to know how long it's going to take me and Williams to be back fighting for podium positions," said Sainz.
"James [Vowles, Williams team principal] said it the other day and calmed everyone's expectations: next year is going to be tough and a learning year before the change of regulations in '26, where I believe the team is investing and the team is preparing to maximise that chance.
"I'm as determined as ever to help that team to be back where it belongs. I personally feel like I belong fighting for wins, podiums and top fives in Formula 1, I've proven it these last four years as a [Ferrari] driver.
"But Williams also belongs to fighting for these top-five and podium places and together with the determination and the strength that we're going to show, the target is to get Williams and myself fighting for those positions in the near future.
"How long that's going to take? I cannot tell you. But I don't think you guys understand and expect how motivated and how much I'm actually looking forward to that challenge. That's one of my qualities, to help a team to perform better and to know which directions to follow.
"And that actually motivates me, having a full team behind Alex [Albon] and me pushing all in the same direction to make a historic team like Williams competitive again. It's tough to explain but some people don't understand how much I'm actually looking forward to it."
You might shrug this off as dissemblance, hiding entitlement and frustration under a thin layer of veneer, but Sainz means it.
The moment he discovered he was on his way out of Ferrari, his focus was immediately on finding the best long-term deal elsewhere. He repeated that mantra publicly and privately, so while he won't have imagined that quest would lead him to Williams despite lines of communication being open with the team late last year, he is fully invested in the Williams revival. He wanted more than a stop-gap.
None of this means he'll be a Williams driver for the rest of his career, but he's signed on with the express intention of putting in the hard yards to help the team's rise. That justifies Vowles's dogged pursuit of him, and the extent to which he's talked him up during the process and after the deal is justified.
Sainz's eagerness to get behind the wheel of the Williams to bank 146 laps on Tuesday, plus the mileage he banked on the promotional event running the day before, shows he's deadly serious.
The test will have been a voyage of discovery for Sainz, but so too for the team. Vowles has talked him up so much that some might privately doubt he's all he's cracked up to be.
But he will have absorbed every scrap of knowledge and information, benchmarked the feel and performance of the Williams against the Ferrari. He claimed after the race on Sunday that he put extra focus on locking in his memory of that comparison to carry into his Williams running, which for some drivers would seem a fatuous claim. Again, Sainz means it.
Those Williams engineers who worked with Sainz will have found an engaged, detail-oriented driver, one who will already have made a positive impression with his feedback and work ethic. There's every chance he will have made constructive suggestions for improvement, likely successfully toeing the fine line between sounding like an entitled 'Big-Time Carlos' demanding everything be like he had it at Ferrari and pushing for every possible gain.
That makes him exactly the driver Williams needs in its quest to climb the order, first to the head of the midfield then ultimately back to winning ways. Sainz can't do it alone, he's no magician and even the most accomplished driver doesn't design the car.
But he's a powerful cog in the machine, one who the team hopes will mesh well with incumbent Alex Albon, who has made the team his own over the past three seasons and now faces a tough challenge alongside Sainz.
Together, they could make a formidable team and both can rise with the Williams tide.
The Sainz/Williams story has begun. Whether it's one of success, failure or somewhere in between remains to be seen, although there's little doubt that 2025 will be every bit as tough as he's predicted. But Williams will have started to realise that Sainz might even exceed Vowles's sky-high expectations. He's that kind of driver.