Daniel Schlosser, who looked after Nico Rosberg's physical preparation, is backing a return to F1 action of 'Miracle Man' Robert Kubica.
Schlosser, who now works with force India development driver Nikita Mazepin, has no doubts about Kubica's physical ability to compete at the highest level of the sport.
"He still has very good muscles in his right arm -- only the volume is not so great," he told Sport Bild.
Many doubted Kubica's ability to drive given the severity of the injury sustained by his right arm in the rally crash that halted the Pole's F1 career in 2011.
But Schlosser is convinced the 32-year-old is up to the task of a full-time comeback.
"Nico (Rosberg), for example, always had a lot of tension in his wrists, so he had to train his arms heavily," he said.
"But other drivers are lighter on the steering due to having a different driving technique.
"Nick Heidfeld was one of them, and probably also Kubica," Schlosser explained.
"They never had to train as much as the others."
Tight left-hand corners are where Kubica's eventual weakness could come in to play. But Schlosser believes an amount of adaptation will compensate for the inadequacy.
"Instead of pressing with the right, you can pull with the left. And depending on the technique, this can even be more efficient."
And so from the evidence seen so far, Schlosser thinks Kubica can return to F1.
"In Hungary, he ran a very difficult programme in high temperatures, which was hard for some young drivers. Anyone who can handle that can also handle a Grand Prix," he said.