Ayr United has been forced to ban English fivers from its ground - after fans flooded the stadium with fake notes.
Bosses ordered a clampdown after food kiosks at the Championship club's Somerset Park were targeted with counterfeit cash.
United managing director Graeme Mathie revealed the dummy money was first detected during the Ayrshire derby clash with Kilmarnock on March 11.
He said his savvy workers are to thank for preventing the club losing a fortune.
Without the ban, the high number of dodgy notes would have left a hole in the club's finances to the tune of thousands of pounds.
He said: "It's been flagged up through the kiosk staff.
"The first game was the Kilmarnock match, I think.
"I'm glad that they identified it was an issue and we weren't awash with fake money that we couldn't bank.
"It's only been on our radar the last three or four games, so probably the last month.
"I think we were lucky that the staff were really proactive with it.
"It was understanding there was an issue, testing the first few and then realising that we had to do something about it.
"They were right to flag up the fact that there was an issue.
"The kiosks are really busy now and it's impossible to check all the notes."
United have posted signs inside their round advising fans staff won't accept £5 Bank of England notes.
Police Scotland have said they have not received reports of counterfeit money being in circulation elsewhere in the community.
One dad, who was at the United's match last weekend versus Inverness Caley Thistle unwittingly handed over a Bank of England fiver at a hot food kiosk - only to be told it was fake.
He had been given the note a few days earlier by an Ayr United employee, he claims.
A staff member kept the note he had handed over, saying it was fraudulent.
The dad said: "I was told English fivers wouldn't be accepted because they'd been flooded with them.
"The worker was very apologetic.
"They said they'd taken in hundreds of fake notes.
"It must've been a lot for them to go to these lengths.
"I got my fake fiver from a pal who works for Ayr United a few days earlier."
A Police Scotland spokesman said: "This is not something officers have made us aware of and we don't have a current warning."
Bank of England launched plastic £5 notes in 2017 but it hasn't stopped crooks making their own fake currency.
Legitimate cash should have a see-through window and the portrait of the Queen.
Big Ben is gold on the front of the note and silver on the back.
The foil patch below also window changes from "Five" to "Pounds" when tilted and the coronation crown appears 3D.
An ultraviolet "5" should appear at the bottom left of the note when a UV light is shined on it.
The circular green foil patch on the back should also contain "Blenheim".
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