On-screen chemistry is something that exists between a film's characters and not between the actors essaying the roles, says Bollywood actress Aishwarya Rai about her success with co-actor Hrithik Roshan.

"Actually the chemistry is between characters that have been written (in script) and not between actors. When the audience experiences a moment that is magical between the characters you guys call it a sizzling chemistry between actors, " she said, when asked about her on-screen chemistry Hrithik ahead of the release of their "Guzaarish" Nov 19.

"It is an interesting coincidence that this is my third film with Hrithik Roshan. It was wonderful working with him. Earlier, we both have acted in two films 'Dhoom 2' and 'Jodhaa Akbar', " she said.

"During 'Jodhaa Akbar' we both had said that we had done two movies which were diametrically opposite in terms of genre and perspective...both the films were hugely appreciated, " she told reporters while addressing a promotional event of Sanjay Leela Bhansali's "Guzaarish" here.

"Dhoom 2" was set up in the backdrop of the 21st century. Hrithik played the role of a thief who steals valuable rare items using various hi-tech gadgets. He fell in love with Aishwarya, who was actually a spy working for the police. The film also had Aishwarya's real life husband Abhishek Bachchan, who played a cop.

On the other hand, "Jodhaa Akbar" was a film which revolved around the romance of Mughal emperor Akbar, played by Hrithik, and his wife, Hindu Rajput princess Jodhaabai, played by Aishwarya.

"Then came Sanjay Leela Bhansali's 'Guzaarish'. We as co-actors were really excited to work in yet again a movie which was so different from the previous two. I think it rarely happens that as co-actors we are working in three movies which are so eminently and distinctively different from each other, " Aishwarya said.

"Guzaarish" revolves around the character of magician Ethan, played by Hrithik, who becomes quadriplegic when one of his tricks goes wrong. Aishwarya plays the role of a nurse, Sofia, who has been accompanying Ethan for the past 12 years.

Ethan's life revolves around Sofia and they share a silent tacit love which is both beautiful and spirited.

"We both maintain and it's true that as actors we always say that chemistry is on paper. It is there on paper in the script and in the screenplay. We actors can only infuse life in it. But if that chemistry is absent in the script, we can try all we want but the moment will never be magical, " said the actress.

"I think when the audience experiences the moment that has actually been written and thought by the director that is all we call a magical moment or sizzling chemistry, " she said.