The senior Roshan will undergo surgery on Tuesday.
Hrithik shared an Instagram post in which he is seen standing alongside his father in a gym.
"Asked my dad for a picture this morning. Knew he wouldn't miss gym on surgery day. He is probably the strongest man I know.
"Got diagnosed with early stage squamous cell carcinoma of the throat a few weeks ago, but he is in full spirits today as he proceeds to battle it. As a family we are fortunate and blessed to have a leader like him," Hrithik captioned the picture in which the father-son duo have struck the same pose.
The note drew speedy recovery and good luck wishes from the film fraternity and fans.
Hrithik's former wife Sussanne Khan wrote: "He is stronger than any superhero. All will go smoothly."
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)