Not since Eric Cantona, just short of his 31st birthday, announced that he was quitting football, has a sporting retirement landed so loudly as a bomb coming out of a clear sky.
Nico Rosberg, himself 31, has performed the trick that is beyond the contemplation of most of the hard-wired folk who participate in high-stakes games - he has walked out at the crowning moment of his career, at a time of his choosing.
Nobody had remotely suggested that he might quit at this point. It was nothing much to do with the fact he may have turned his back on something like £100million - five years at approximately £20million a year (his current contract is worth £18.3m all bonuses told). It was a case of why would he? That he would carry on seemed so obvious that the question was never asked.
The mood at Mercedes was one of shock when the news came on Friday afternoon.
His statement via social media amounted to the most incendiary thing he has ever done in a career that operated along Teutonic lines of perfection - a quiet life, unrelenting graft, a dedication to analysis of engineering data.
He also revealed a lot about himself in his parting words: that he had found the sheer tension of fighting for the title, which he won in Abu Dhabi just five days ago, almost crippling.
He also underlined his status as a family man who wanted to repay his wife, Vivian, his childhood sweetheart, who had made every sacrifice, including acting as a virtual single mother to their young daughter Alaia, so that 'they' could win the title.
Born the rich son of 1982 champion Keke, he never really wanted for money, and the fortune he has made since his debut in 2006, means he certainly doesn't now. So it is for a home life that he casts himself away from the pit lane.
For me, having watched his debut 11 seasons ago in Bahrain, there is a keen sense of an unexpected passing. He once told me on a long flight we shared seat-by-seat that he wanted to go into driver management, so this is what I expect he might do, after a pause for some relaxation.
He will be remembered as a very good driver, one who made the most of his gifts, but not a great one. But he beat one of those greats, Lewis Hamilton, and that triumph of his character in that fight will always define him.
The other thing that we will never forget is the manner of his leaving: he beat Lewis after all those years of trying going back to their days as dreaming karters, and then he walked off into the sunset.