Having succeeded in his goal of becoming 2016 World Champion, emulating his father in the process, Nico Rosberg announced his retirement from the sport with immediate effect. When the driver's line up on the grid in March there will be no defending World Champion amongst them.
This has happened twice before in F1 history - in 1993 Alain Prost retired after strolling to hos fourth World Championship in his Williams-Renault; whilst back in 1970 Jochen Rindt died at the Italian Grand Prix, clinching the title posthumously at the end of the season.
Rosberg beat Lewis Hamilton over a season, despite the latter being universally accepted as the faster driver. Hamilton's complacency (Rosberg won the eight races on the bounce from Hamilton's title victory last season); poor starts and a couple of weekends where he was just woeful; meant that Rosberg's consistency and better technical understanding carried him through to the title.
The prospoect of having to do it all next year probably wasn't overly appealling and Rosberg's call to switch from racing driver to family man probably wasn't that difficult to make in the end.
Through it all Rosberg remained the classy guy. Like Jensen Button and Felipe Massa, who retire with him, the sport will be poorer for their absence.