It happened during an UEFA Youth League match between Celtic and Valencia at Celtic Park.
Hoops striker Jack Aitchison was chasing down a ball over the top as Valencia defender David Ruiz came across to cover.
When the defender misjudged the flight of the ball he appeared to throw himself to the ground.
The referee gave the free kick and was met with widespread disbelief from the Celtic players.
But Valencia revealed after the match that 78th-minute substitute Ruiz had torn a ligament and that was why he had hit the deck.
The match ended 1-1 after Valencia scored a late equaliser, and Celtic eventually lost on penalties.
• An earlier version of this article did not address his injury which was later confirmed by Valencia. We apologise for the omission and pass on our best wishes for a speedy recovery
THE SCOTSMAN ON SOCIAL MEDIA