Incidentally, the actors not only share their birth dates, but both turned 43 years on Friday.
Media reports suggest that Saif might be spending the day with his wife Kareena Kapoor, who has flown to Los Angeles (where Saif is currently shooting) to celebrate her husband's special day.
Saif, who hails from a royal family, is the son of cricketer and last titular Nawab of Pataudi, late Mansoor Ali Khan Pataudi and actress Sharmila Tagore, a great-grandniece of world bard Rabindranath Tagore.
Saif made his Bollywood debut in 1992 with the film 'Parampara', where he shared screen with Aamir Khan, Raveena Tandon and Neelam Kothari. The film was declared a flop at the box office.
In between 1992 and 2001, the actor featured in films like 'Main Khiladi Tu Anari', 'Yeh Dillagi', 'Bambai Ka Babu', ' Kachche Dhaage', 'Aarzoo', 'Kya Kehna' and others, but was never praised for his performance and was often criticised.
After struggling for nine years in the industry, the actor rose to stardom with 2001 film 'Dil Chahta Hai', which marked a turning point in his career.
After 'Dil Chahta Hai', his success story continued with films like 'Kal Ho Naa Ho', 'Hum Tum', 'Salaam Namaste', 'Parineeta', 'Being Cyrus', 'Omkara', 'Race', 'Kurbaan', 'Cocktail' and 'Race' series among others.
The actor bagged the National Film Award for Best Actor in 2004 for his role in the film 'Hum Tum' and six years later, Saif added anther feather to his crown, as he was conferred the Padma Shri award in 2010.
Apart from acting, Saif produced four films including 'Love Aaj Kal', 'Agent Vinod', 'Cocktail' and 'Go Goa Gone'.
Throughout his stardom, the actor got involved into various controversies. In 1998, Khan was charged with poaching two blackbucks in Kankani during the filming of 'Hum Saath Saath Hain'.
Again, in 2008 Khan was involved in assaulting a photographer while filming 'Love Aaj Kal'.
Saif married actress Amrita Singh in October 1991 and they have two children, Ibrahim and Sara. After thirteen years of marriage, the couple divorced in 2004.
The actor then dated a Swiss model and finally got married to Bollywood actress Kareena Kapoor in 2012.
Saif's upcoming films include 'Bullet Raja', 'Happy Ending', 'Thagi', 'Nawab The Nautch Girl And The John Company' and 'Judwa 2'.
On the other hand, actress Manisha Koirala, who has recently defeated cancer to win back her life, said she will have a small get-together with friends to celebrate her birthday.
In an interview to DNA newspaper, she said "My friends want a party. Not a big bash, just a small get-together. Honestly, life is a celebration for me. It has always been. But now I value every moment."
Manisha's debut film in Bollywood 'Saudagar', where she shared the screen with two legendary actors, Dilip Kumar and Raaj Kumar, was a huge hit.
She starred in films like '1942: A Love Story', 'Agni Sakshi', Gupt', 'Bombay', 'Lajja', 'Moksha', 'Ek Chotisi Love Story', 'Dil Se..', 'Company' and few other hit films.
The actress has made her mark in the industry with her power packed performances in films like 'Bombay', 'Akele Hum Akele Tum', 'Khamoshi: The Musical', 'Dil Se', 'Company', and 'I Am'.
Manisha has thrice won the Filmfare Critics' Award.
The actress has been involved into various philanthropic works like promoting women's rights, prevention of violence against women, and also to prevent the human trafficking of Nepali girls for prostitution.
Both Saif and Manisha, after spending more than two decades in the industry, have done only one film together, 'Kachche Dhaage'.