Nico Rosberg has shocked the F1 world by announcing his retirement from the sport, only five days after clinching his first world title.
The 31-year-old German driver won nine of this season's 21 grands prix, beating three-time champion and Mercedes team-mate Lewis Hamilton by five points.
In a Facebook post, Rosberg said his "one goal" in 25 years of racing was to become world champion and could retire following his victory in Abu Dhabi on Sunday.
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"I have climbed my mountain, I am on the peak, so this feels right," he added.
The announcement has stunned media and fans alike. Rosberg's wait for his first world title is the second-longest in history, spanning ten years and 206 races, and he was expected to challenge Hamilton to retain his title next year.
However, the move is not unheard of - French driver Alain Prost retired while reigning world champion in 1993.
BBC Sport F1 writer Andrew Benson suggested more people should have seen Rosberg's retirement coming.
"While thinking about how hard winning that title was, doubtless his thoughts were also about what it would take to beat Lewis Hamilton to it again," Benson said.
"He clearly felt that at the age of 31, with a young daughter, he was not prepared to make those sacrifices again."