Grodin and Candice Bergen will play Fox's broadcast journalist character Mike Henry's parents on the show.
"I filmed my first day [this past] Monday and they asked me to do it last Thursday," the 78-year-old actor and radio personality told the New York Post.
"I really don't understand [the timing] myself," Grodin said. "The most striking part is that I had never met Michael J. Fox until now. ... I was certainly aware of him and he's really quite inspiring. These are very long days [shooting the show] -- and I'm healthy it seems to me -- and then I look at this guy and it's amazing."
The show mirrors Fox's real-life experience of returning to the workplace after being sidelined for years by Parkinson's disease.