Head to head betting - potentially the greatest betting rort since the Romans' prisoners played the lions.
And racing's integrity unit says it can do nothing to stop it or possibly even police it.
The TAB recently introduced head to head betting, pitting two horses and/or two jockeys against each other in selected races. Seems innocent enough - except that if jockeys decide to take advantage of it, it will become the easiest punting opportunity of all time to rort.
Here's how it could work: Lester Piggott, riding Sunline, could say to Malcolm Johnston, rider of Bonecrusher, the other head to head horse, "Hey, Malcolm, Bonecrusher races back and I'm going to lead. Head straight to the rail behind the field from your wide draw and be unlucky enough to make sure you don't beat me home.
"We'll both back Sunline in the head to head."