A new “unreturnable” spin-serve has caught the attention of the world’s top badminton players and the Indian doubles shuttlers are also not far behind as they are putting in the hard yards to master this latest skill, which many believe can give “unfair” advantage to the players.

“We have been trying this for many days but couldn’t figure it out,” India’s doubles ace Satwiksairaj Rankireddy, who forms the world no. 5 pair with Chirag Shetty, told PTI from Hyderabad.