Two cards match under impossible conditions!
The magician explains he has two decks, one red the other blue. He places the blue deck aside explaining he will come back to that deck later. The other (red) deck is then opened and shuffled by the spectator, never touched by the magician at any point throughout the routine. Once shuffled and seen to be all different, they are then spread face down by the spectator all over the snooker/pool table, covering as much of the table as possible.
The white snooker ball is then used, with any starting point chosen by the spectator, hit anywhere on the table, thus randomly selects a playing card. The card the white ball lands closest to is the one that will be used for the effect. The spectator can even have the choice to hit the ball again if they wish to select another card, it really is that free. All other surrounding cards are removed and the selected card is moved to the center of the table, still face down by the spectator. You never touch the selected card. The other deck now comes into play.
The deck is opened and spread, with one face down card seen. This is also placed face down onto the center of the table, next to the other card. One blue back and one red back card are now facing down on the table. Both are turned over by the spectator and are seen to match. The card randomly selected by the spectator with the white ball matches the one and only face down card in the other deck.