On 27 September, a few days before shooting is due to start, Björnstrand goes for a medical check-up. There are many twists and turns to this story, yet according to his wife, the writer Lillie Björnstrand, the check-up was at Bergman's insistence, under the premise that the role was so demanding. Björnstrand protested that he was in robust health, but the SF company doctor prevailed and carried out the examination. The diagnosis was high blood pressure and he was placed under strict doctor's orders: no alcohol, no sex, etc. Otherwise, he warned, the actor would be at risk of cerebral haemorrhage and paralysis. On the other hand, the doctor saw no reason why he should pull out of the shooting, despite Lillie's entreaties.
'Gunnar was frightened to death. He couldn't sleep, couldn't banish the thoughts of death and paralysis from his mind. It was sheer hell. We stayed awake during the nights that remained before he was due up at the film shoot in Dalarna.' When he arrives at the studio the next day, the atmosphere is strained. In his book of interviews Vilgot Sjöman recounts a question he asked Bergman that day: 'You look so goddam smug when you speak of Gunnar's illness.' Bergman laughed and said: 'Well, of course it is wonderful that Gunnar is so off-color and unwell when heäs to play this sort of part. Imagine if I'd gotten a sun-tanned, hale-and-hearty guy to play someone worn out and ailing!'
It is disagreeable to think that the director to some extent welcomed the illness for the sake of the film, yet the situation was to take a further turn for the worse. Björnstrand is so upset by the news that he decides to get a second opinion, and is examined by the heart specialist Clarence Craaford. The results were the exact opposite: his blood pressure was considerably lower, there were no risks either for a heart attack or a cerebral haemorrhage. Craaford also discarded half of the medicines previously prescribed for Björnstrand and after a week he stopped taking any medicine and felt fit once again. It is impossible to apportion any blame, but is clear that Björnstrand himself believed that his director had manipulated him in some way into believing that he was ill. Although Björnstrand did not say so in so many words, the perceptive Sjöman discerned something in the relationship between the two:
"There is a tension between Ingmar and Gunnar. It has evidently increased the last few days. What it consists of I don’t really know yet. With Gunnar I notice a feeling of not being free; an idea that Ingmar has a deep contempt for actors, 'And when you've done a good job, you still don't get the credit for it yourself.' With Ingmar I notice an aggressiveness which he cannot camouflage: his tone is sharp, and Gunnar tightens up still more. Gunnar is silent or aggressive in return. Ingmar seems disappointed. Gunnar too. How is that tension going to affect the film?"
Even after he is declared fit, Björnstrand is still shattered. The role is a difficult one, made all the more difficult by the suspicion that his friend Ingmar has deceived him. Bergman continues to appear unaffected. At one point the make-up artist Börje Lundh is worried that Björnstrand's appearance has changed; that he has become noticeably thinner. They ask Bergman what they should do, since the first half of the film is already in the can: 'It doesn't matter if he's a bit hollow-cheeked. Good thing, in fact. Lose a bit more weight!'