Now it can be told. The reason Maddy and Vidya look so much in love is Maddy's 2-year old son Vedant. The child bonded so beautifully with Vidya on the sets of Guru that she became a part of Madhavan and his wife Sarita's inner circle.

All said and done, it's just an ad. But the chemistry that Vidya Balan and Madhavan share in the ad for a mobile company has spurred movie makers to plan at least a couple of movies with them together.

In fact, the cell phone company has now decided to put out a series of ads featuring Madhavan and Vidya as a couple connecting emotionally on the phone. Madhavan has been running in and out of Mumbai to complete these ads.

Says the busy Southern star, "Initially, I was only the brand ambassador for Airtel's southern market. But now they've signed me on for the whole country. And we've shot a series of ads with Vidya and me. For the last one week I've been running in and out Mumbai and Chennai. During the day-time I'm in Chennai shooting for a Tamil film. Then I take a night flight to Mumbai to dub for the ads."

Curiously Maddy and Vidya have hardly shot together for these ads about love and togetherness. "We've just done one shot together. The rest has been shot with the two of us separately. It's strange; people have noticed so much chemistry between us when we aren't even together in the ad. My wife Sarita loves the ad. She thinks Vidya is better than me in the ad. But then she's my harshest critic. All three of us Sarita, Vedant and I adore Vidya."

Vidya has done ads prior to her acting career. This is her first ad post-stardom. She thoroughly enjoyed doing this new yet old experience. "Years ago, I was supposed to do Tamil film with Maddy. Then we were also supposed to do a Deepa Mehta film together. I think Maddy and I were destined to special things in limited space. Both of us had cameos in Mani Ratnam's Guru. People still talk about our romantic scene in the rain (including a kiss). Now the Airtel ads. It's unbelievable how much chemistry people have seen between us in those few seconds. I always say it's the moments that make a romance. "