After watching Sushmita Sen and Sanjay Dutt on Karan Johar's "Koffee with Karan" chat show, two producers have reportedly decided to cast the hot pair together.

Another untried pair, Aamir Khan and Aishwarya Rai, were slated to come together in "The Rising". But when Aishwarya demurred, Aamir fell into a deep sulk.

Now, if all goes well, the untried pair might finally burn up the screen in Aditya Chopra's next venture.

Salman and Aishwarya shared tremendous on-screen bonding in "Hum Dil De Chuke Sanam".

Vivek Oberoi and Aishwarya didn't share it in "Kyun... Ho Gaya Na".

It isn't really crucial for a couple to jell well in real life for the screen to burn up. Koel Purie and Rahul Bose weren't even on talking terms while they shot some of their warmest scenes in "White Noise".

They looked convincing as a couple. So what makes a pair work on screen?

Why did it take Hema Malini and Amitabh Bachchan more than 30 years to discover a common ground in "Baghban"?

Sure, they worked together in hit films like "Naseeb", "Kasauti", "Desh Premee" and "Satte Pe Satta". But somehow both the superstars together never created the same ripple effect as Amitabh and Jaya Bhaduri or Hema and Dharmendra.

After having formed the most unusual and stunning pair with Rani Mukherjee in "Black", Amitabh is now on the lookout for suitable co-stars.

One unusual entrant into this field of on-screen pairing is Shefali Chaya, director Vipul Shah's wife who plays the Big B's wife in "Waqt: Race Against Time".

When the idea of casting his wife first came up, the director wasn't very sure whether the couple would look correct. Shefali went through several rounds of make-up before she was convinced she was worthy of being Amitabh's better half on screen.

Thank god for the change! Audiences are otherwise subjected to the same set of pairs in recurring combinations.

So how about Saif Ali Khan and debutante Vidya Balan in Vinod Chopra's "Parineeta"? And how about Salman Khan and the Aishwarya look-alike Sneha Ullal in "Lucky..."?

Haven't we seen enough of John Abraham and Bipasha Basu? So how about John and Esha Deol in debutant Soham Shah's thriller "Kaal"?

"I hope audiences like Esha and me together as much as they liked her with Uday Chopra in 'Dhoom'. Then she can be my lucky mascot as well," says John Abraham.