Niki Lauda is back in hospital in his native Austria, five months after a lung transplant.
The triple Formula 1 world champion, and Mercedes’ non-executive chairman, is understood to have suffered a serious bout of the flu, and has been admitted to intensive care in Vienna.
Lauda, 69, underwent his life-saving lung operation in August before he was released for rehabilitation nearly four months later. He has been in his role at Mercedes since 2012 but his poor health meant he missed the second half of last season.
Mercedes staff paid tribute to Lauda at their Northamptonshire factory by celebrating both the team’s and Lewis Hamilton’s championship honours by wearing red caps similar to the one usually worn by the Austrian.