Williams has revealed it first approached Carlos Sainz about an F1 drive in Abu Dhabi last year, before anyone knew Lewis Hamilton would replace him.
Following months of intrigue about Sainz's future, it was announced on Monday that he had agreed a deal that will commit him to Williams for at least the next two years.
It came after the Spaniard had courted offers from Sauber/Audi and Alpine, while he had also held out hope of Red Bull or Mercedes opening doors for him.
But the decision to commit to Williams comes after its team principal James Vowles said it had been clear for months that Sainz was his number one target, and that an approach had been made even before it became clear he would be leaving Ferrari at the end of this year.
"The conversation has been many months," explained Vowles in a call with media on Tuesday.
"It hasn't been weeks, of which you've been privy to some of it because it's been a bit more public than I would normally do with a driver discussion, but it actually started way back in Abu Dhabi last year."
While Sainz did not appear to be on the open market at the time, and many expected him to remain at Ferrari from 2025, Vowles said he approached him at the F1 finale because he felt he had a chance of winning him over.
"There's only one driver I spoke to in Abu Dhabi last year, only one, and it was Carlos, just to be super clear," he explained.
"I didn't spread bet. I went for one driver that I thought would make the difference."
Vowles believes that, off the back of his team finishing seventh in the constructors' championship last year, Williams could make enough progress to convince Sainz to jump ship from Ferrari.
But those hopes fell short when Williams' 2024 campaign started on the back foot due to its car being overweight.
"I thought, for complete transparency, that we wouldn't have the weight on the car, and you don't know the numbers, but if we would have been in a points-scoring position every weekend, I actually think it would have been a more difficult choice for him [to stay] if Ferrari was more on the rocks, and I didn't know that it would be.
"My point was to position myself in the most sensible way possible for that. But performance drives everything. If you're in the points you have a lot more phone calls than if you're not."
It was only when Hamilton's Ferrari deal for 2025 was announced in February that Vowles knew his chances of landing Sainz had been considerably improved.
Asked if he knew about Hamilton in advance, Vowles said: "I had no inkling at all. That was a complete shock to me.
"When Lewis was announced, absolutely no idea. I knew Lewis had his heart set there eventually, but I also know the end of that deal, because I was a part of it, and I was knocked off my chair the day that that happened."
While Vowles held talks with other drivers in recent weeks, including Valtteri Bottas and Esteban Ocon, he said that was only done because there was a fear that the Sainz deal was going to fall through.
"I didn't call or contact anyone else," added Vowles. "In fact, the only time I did was later in the programme where it became very clear that Carlos may not join us.
"And at that point, I've got to make sure that I put my eggs in multiple baskets to cover it off. But he's aware of when I did that, and it was very late on in the process."
While there have been rumours in recent weeks that one of the elements Sainz wanted before committing to Williams was an exit clause that allowed him to join Red Bull or Mercedes if a seat opened up, Vowles has clarified that such an element does not exist.
Asked about the rumours that have appeared in some media about an exit clause, Vowles said: "There are precisely 10 people in the world that know what the interior of the contract holds, just 10.
"And I guarantee you, none of you on the call is it, no one in this company is it, and particularly sat around me at the moment. The Carlos camp know, and I know what's inside that. So anything you've read on the internet is speculation, and that is it.
"The message that [the deal is for] '25 and '26 and beyond did not come from myself, that came from Carlos. He wanted it to be abundantly clear to all of you, to the world, that he has committed and this is where he wants to be."
