Britain's Got Talent 's last auditions of the current series saw a final magician attempt to impress the judges ahead of next week's live semi-finals.
Kimoon Do, aged 31, revealed he had travelled from South Korea to be on BGT and perform his card trick.
The magician soon had the audience and the judges laughing with his comedic yet clever magic act, which left Simon Cowell baffled.
He, Bruno Tonioli, Alesha Dixon and Amanda Holden all shared they had no idea how he did the trick, while host Ant McPartlin was also left shouting out in confusion.
Kimoon headed down to the judges' table to begin his act, where he revealed he had a special card not normally found in the standard decks.
It featured a blue arrow on it, and he revealed it would help him fix any mistakes when guessing different cards at different times.
Kimoon then asked judge Simon to shuffle his cards for him, consisting of four aces, before getting Amanda to pick one at random.
She picked the ace of spades and showed it to the crowd, before handing it back to him.
As the magician then managed to find all of the aces from the pack one-by-one, he then claimed to be missing the number nine card before the card with the blue arrow in appeared back in the pack.
He "used this card" to locate the number nine, which was now in his jacket pocket in the place of the blue arrow which was now in his hand.
Kimoon then placed all of the aces into his empty wallet, except for the ace of spades which went into his pocket.
But as he continued working his way through the spade suite, he instead placed the very same ace cards onto the table and found the missing cards in his wallet.
First he showed the Jack and the Queen but the third card was the blue arrow, until he turned over the card that was now in his pocket.
It's then that the third card changed to the King before the eyes of the judges while it was still in his hand, without him turning it around or hiding it.
The card in his pocket transformed instantly into the blue arrow that had just been in his right hand seconds earlier.
As the judges looked puzzled and the crowd cheered, host Ant shouted: "Oh my God, what? What?!"
Simon told the hopeful: "It's impossible to explain what just happened. I thought it was incredible."
Amanda then said it was "utterly charming" as Bruno added: "I could not work out how you did it!"
But many viewers on Twitter and YouTube believed they had it all worked out, with some claiming to notice a "mechanism" on one of the cards, and others suggested he was hiding cards in his sleeve.
Other viewers stated it was "clear" that the arrow card had a double, or it was folded, making way for the trick at the end.
One viewer commented: "Great trick, but due to the lighting you can see the fold between the Arrow card and the King card at the end where he flips it."
Another said: "you can see where he hides the arrow in the deck and places another in his Jacket pocket."
A third viewer wrote: "I didn't notice anything surprising here, only here 1 in slow motion it can be seen that the card opens at the end, which means that a mechanism is installed in it."
Meanwhile, one fan commented: "it's obvious that the card in his right hand is split in half and there's another card on it but it's folded."
Britain's Got Talent's live semi-finals begin on Monday at 8PM on ITV1 and ITVX.
