Sebastian Vettel is set to lose his physiotherapist and trainer Tommi Parmakoski.
After securing his back-to-back drivers' world championship in Japan two months ago, Vettel paid special tribute to the Finn.
"He was the one not allowing me at any stage this year to lose the grip, start to fly, or think about things that are not in our control," the Red Bull driver said.
"It is down to people like Tommi who push more than 100 per cent to do his job and keeps us on the right track," added Vettel.
Parmakoski, 28, said in 2011: "At the race track Sebastian is the boss. Away from the track, I am."
Germany's Auto Motor und Sport reports that, after three years together with Vettel, Parmakoski - a former ice-hockey goalkeeper - has accepted an offer to coach a Finnish women's hockey team.
The report said Vettel is seeking a replacement.