One of the most deadly arts in the fast bowler's arsenal is that of reverse swing.
WikiHow
Pioneered by the likes of Imran Khan and Sarfraz Nawaz and perfected by Wasim Akram and Waqar Younis, it was a potent weapon which left some of the best batsmen clueless.
So what is it actually? Many alleged ball tampering, but in reality it is simply a good usage of physics.
Well in conventional swing, the ball needs to be new, but as it wears off, the aerodynamics change drastically.
It begins to swing towards the shinier side, which is not the case when you are bowling a normal swinging delivery. Thus the batsman expects the ball to go one way but it goes the other.
The result is always a swing to the side with the later separation, so the swing is away from the seam.
The biggest problem for batsmen is that reverse swing occurs late in the ball's trajectory. This means that he is already committed to playing the swing one way, which will be the wrong way to address swing which is suddenly coming from the opposite direction.
The best reverse swing deliveries are believed to have been bowled by Wasim Akram, which saw him get 2 wickets in 2 balls in the 1992 World Cup final.
For England it was Andrew Flintoff and Simon Jones, while India saw the pair of ?Zaheer Khan and Ajit Agarkarv execute it to good effect.
Be as it may, there is no tampering of the ball involved to get the ball to go the other way. In the end it's pure since and a bit of skill. It is that one ball in the bowler's arsenal which can come in handy in a pressure situation and reverse swinging deliveries have been known to change the complexion of a game.