51 Times More Difficult (Gimmick and Online Instruction) by Henry Evans

A card is selected and put back in the middle of the deck. The magician says he will make the card magically turn face up, but then he says he has a better idea-to make it 51 times more difficult. So he tosses the deck on the table and instantly all cards are magically face up except for one, the selected card, which is the only one face down in the middle of the spread.

It is automatic, no sleight of hand needed.