Hamilton has won six of his world championships and 82 of his 103 career race victories with Mercedes, but having not won a race since the 2021 Saudi Arabian Grand Prix, has decided to pursue an unprecedented eighth title elsewhere.
It means teaming up with the most iconic and successful team on the Formula 1 grid, following in the footsteps of the only other seven-time champion in Michael Schumacher by driving with the Maranello-based outfit.
Now, Haug has said quite how the news took him by surprise, having expected Hamilton to stay with Mercedes for the rest of his career.
Haug served as vice president of Mercedes' motorsport activity from 1990-2012, and saw Hamilton start his career in F1 with the Mercedes-powered McLaren team.
“If I had a bet on one thing, on a combination in Formula 1 that would last forever, it would have been Lewis Hamilton and Mercedes,” he told Motorsport-Magazin.
“I was completely blown away, I would have sworn that it would stay that way forever and that he would stay with the silver star as a brand ambassador or whatever afterwards.
Haug also believes that other Mercedes staff members may follow Hamilton from the German's old team to Maranello.
“I think so, yes. But it can’t be avoided,” Haug continued. “For me, he’s perfect.
“What records has he set in Formula 1? Why do people say that Formula 1 has a single superstar?
“Of course [Max] Verstappen is the fastest, he’s maturing, but all the statements from Lewis, his performances, his work off the track, his fight for equal treatment. That’s very remarkable.”