World of sport shocked as Rosberg hangs up the racing gloves

"We started out when we were 13 and we would always talk about being champions and when I joined this team Nico was there - again, which was something we talked about when we were kids," Rosberg's Mercedes team-mate Lewis Hamilton said.

"It's definitely going to be very strange and for sure I will be sad not to have him in the team next year."

Rosberg clinched his first world championship at the season-ending Abu Dhabi Grand Prix just five days ago, beating three-time winner Hamilton to the title by a narrow margin.

The decision not to compete in 2017 suddenly opens a race seat at the dominant world champions Mercedes but team boss Toto Wolff reacted calmly to having a new problem to solve.

"He has chosen to leave at the pinnacle of his career, as world champion, having achieved his childhood dream," Wolff said. "The clarity of his judgement meant I accepted his decision straight away when he told me."

Governing body FIA president Jean Todt said he was "very surprised, as I'm sure everyone is, but Nico has demonstrated across the year that he is extremely brave.

"I think he did five or six of the hardest laps of his life in the final race of the championship but the consequence is that he made it."

Current F1 drivers Nico Huelkenberg, Romain Grosjean and Kevin Magnussen all spoke of their "respect" for Rosberg while Marcus Ericsson also told him to "Enjoy your next chapter in life."

The 1996 world champion Damon Hill said on Twitter: "Well done Nico. More to life than chasing round in circles. Respect."

Outside the world of racing, tennis great Boris Becker and Germany's Nordic combined star Eric Frenzel also paid tributes.

But not everyone could understand giving up a lifetime of dedication by quitting having finally reached the top.

"Everybody has their reasons for everything, but I really don't know," nine-time Olympic sprint gold medallist Usain Bolt said. "I guess he felt like he has gotten what he wanted."