Priyanka Chopra is said to be going through tremendous turmoil and stress because of her father's frail health. It was evident at a recent shoot when the actress faced the camera with Sanjay Dutt for Apoorva Lakhia's "Zanjeer".

Priyanka kept forgetting her lines, says a source.

"It was not like Priyanka at all . She is never known to forget a single line. But there she was standing in front of Mr.Dutt, faltering and fumbling over her lines repeatedly," the source said.

Sanjay was indulgent and understanding as he himself began to forget his lines on seeing Priyanka doing the same.

This is said to have gone on for hours, as the leading man Ram Charan Teja who has his own problems with the Hindi language, sat patiently and waited for his two co-stars to get their act together.

"Priyanka said she was forgetting her lines because she was overawed by Mr.Dutt's presence. But we feel it was something a lot deeper. Priyanka is not known to lose her cool under the most trying circumstances," said the source.

A friend reveals how her father's illness has indeed begun to take toll on Priyanka's concentration.

"Outwardly, she is doing fine... Going about all her duties as per schedule. And god knows, her plate is more than full at the moment, what with her international singing career and a slew of Bollywood projects happening simultaneously.

"But Priyanka is deeply troubled by her father's illness. She will never talk about it with any of us, not even her mom or kid brother. When her father had first been diagnosed with a serious illness some years ago, Priyanka didn't even mention it to her friends. She is a very strong girl. She can take any kind of adversity in her stride.

"Just see how calmly and confidently she dealt with all the backlash regarding her friendship with Shah Rukh Khan. But this (her father's illness) has overpowered her equipoise," said the friend.

Priyanka is extremely close to her father, and even has a tattoo - "Daddy's Li'l Girl", on her wrist.

Priyanka's doctor father, Lt. Col Ashok Chopra, retired from the Indian Army in 1997.