"I did direct him in two advertisements. I did feel hesitate to tell him anything but he is good at what he does.
It is difficult to direct him but I am looking forward to work with him," the 52-year-old helmer said.
Hirani was speaking at the teaser launch of "Wazir", which he has edited. The film has been directed by Bejoy Nambiar.
"I am a big fan of him (Bachchan). As a child I used to speak like him, get clothes stitched like him, listen to his father's poems that he recites. I remember when he came to my place he did recite his father's poems and I have recorded that and kept it. It is a precious possession. It is a joy to hear it," the "3 Idiots" director said.
Hirani also revealed that he would soon start work on his next film -- a biopic on Sanjay Dutt.
"I am still writing the script... we are working on it. Next year we will shoot," he said.
There are reports that Deepika Padukone will be acting in this film.
"As of now I have only spoken to Ranbir...not met anyone yet for the casting," Hirani added.
