Nico Rosberg's physical trainer is unclear about what Nico Rosberg's current motives are.
Daniel Schlosser, a man who worked closely with Rosberg for many years, was also shocked by his sudden decision to retire as world champion.
"For me, everything came very suddenly," he told Bild newspaper.
"I'm exploring my options because I would be very happy to stay at Mercedes, and I would also like to work in my home town of Cologne or cooperate with another driver or sportsman," Schlosser added.
However, he ruled out simply switching sides of the Mercedes garage, to work with Rosberg's former teammate Lewis Hamilton.
"It's not a question," said Schlosser, "because he is happy with his physiotherapist as far as I know. And we have been in competition for so long that it would be hard for me."