Mercedes boss Toto Wolff has revealed it was Carlos Sainz's father who told him that Lewis Hamilton was joining Ferrari in the days before he heard the bombshell news from the seven-time world champion himself.
In a transfer development that absolutely stunned F1 back in February, Hamilton enacted a break clause in his then-new two-year Mercedes deal to sign with Ferrari for next year in a move that will see the Briton replace Sainz in the Scuderia's line-up from January.
At the time Wolff said he had "heard the rumours a couple of days earlier" about the news before Hamilton himself told him over breakfast at his house in their usual start-of-year meet-up.
Nine months on and Wolff has now revealed where those murmurings first emerged - with Carlos Sainz Snr, the two-time World Rally champion, the source.
"I heard the bells ringing two weeks before," Wolff said on The High Performance Podcast.
"The old man Sainz called me and said 'this is what's happening'. Then there were a few drivers that rang me up that didn't before so I thought 'ok, there is something going on there'.
"Then I sent a text to [Ferrari team principal] Fred Vasseur saying 'you're taking our driver?' Didn't get any response - very unusual for Fred, he's a good friend. So we saw it coming."
Wolff said he had not been tempted to contact Hamilton before their scheduled meeting.
"That was a situation where I just wanted to see how it was happening and leave it to him to and to Fred to tell me that they were doing this," he added.
Wolff on what Pep told him about stars who want to leave
The Mercedes team principal also spoke about past advice he received from Manchester City manager Pep Guardiola about to how to handle stars who want to depart.
"If somebody decides to go then you need to let them go," said Wolff, who has built a friendship with Hamilton during their 12 years at Mercedes.
"I had a chat with Pep Guardiola a long time ago, and he's a friend, and I said 'what do you do if this and that player leaves' and he said: 'What do you mean [what do] I do?'
"I said 'well, do you try to convince them to stay?'
"[Guardiola replied] 'No. [If] somebody thinks he can play elsewhere better or earns more then you've just got to let them go'.
"This is something I embrace in the same way here. If somebody wants to go then let's make it as good as possible for each of the parties."
Formula 1 returns with the Las Vegas Grand Prix on November 22-24, live on Sky Sports F1 where Max Verstappen could seal the championship. Get Sky Sports F1 to watch every race and more live
