The actor plays a Tamil IAS officer in the political thriller, and it is rare for him to take off his shirt.
"It's not a towel... It's a south Indian lungi, " Abhay said, flashing his dimpled smile at a press conference here Monday.
In 2011, it was reported that Abhay insisted on wearing a vest for the song "Paint it red" for the movie "Zindagi Na Milegi Dobara".
In "Shanghai" he was apprehensive about wearing just a lungi.
"I cried many days that why you're making me wear this... but then we decided to go with it. I told Dibakar to take care of the lighting... that's all, " said the 36-year-old.
Unlike most actors who focus on building the perfect abs for a topless scene, Abhay kept his physique normal for "Shanghai".
"Dibakar said I shouldn't go and make a gym body with six packs. He said - 'Be athletic, keep your physique as it is, don't pump yourself with steroids otherwise you won't look like an IAS officer for sure', " Abhay said.
Banerjee says the focus was more on the scene, rather than Abhay's body.
"While filming that scene, we weren't really thinking what Abhay would look like because it was a one-take scene when a burning brick wrapped in cloth and kerosene oil had to crash in through a window to the left of Abhay and landing to Abhay's right side, and keep burning. There were three risks - it could have hit Abhay, it could have hit the camera or it could have hit the laptop in front of Abhay.
"We were really nervous about it. So that time how Abhay looked hardly mattered. But in fact, I remember I wanted him to grow a slight paunch for it... I am sure he would have done it... but we didn't have time, " said the filmmaker.
"Shanghai", releasing Friday, also features Emraan Hashmi and Kalki Koechlin.