Ranbir and Deepika, who started their Bollywood journey eighth years ago, have previously worked with the 44-year-old director in "Rockstar" and "Love Aaj Kal", respectively.
When asked if "Tamasha" will turn the tide for Ranbir, whose recent films have failed at the box office, Imtiaz told PTI, "I hope so. These things are far too transient. The career graph is just a dot in the time line, it changes all the time. I hope for both of them, 'Tamasha' becomes a high point."
"I know as actors, and for me as a director, we have gone to a different level in the work that we have done with 'Tamasha'. I hope the same happens in terms of stature for both of them."
The film marks Ranbir, 33, and the "Piku" actress' third outing together after their 2014 blockbuster "Yeh Jawaani Hai Deewani" and "Bachna Ae Haseeno" in 2008.
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The chemistry the former couple share on-screen has become a favourite of young movie goers, but Imtiaz insists that it is a well written role which creates chemistry and not the real life connection they have.
The "Rockstar" helmer, who also worked with former couple Shahid Kapoor and Kareena Kapoor Khan in "Jab We Met", believes it is not necessary that actors who have been in a relationship will add a certain nuance to the characters.
"It is not at all necessary. It really depends upon the characters and it depends upon the people these actors are. The fact that they are having a relationship, or have had it will not really make too much of a difference.