Irish lottery players are up in arms, claiming that one of the balls in Saturday's £4.5 million draw had two different numbers on it - but the organisers say it was just a trick of the light.
Punters watching the live Lotto Plus 1 draw on RTE say that one of the winning balls - 38 - also had the number 33. And more than one posted a photo on social media, questioning whether the draw was a fix.
"Fixed Irish lotto, look at 33 & 38 on the same ball?" wrote one. Another commented: "Clear as day a total fix". Some viewers suggested that the lottery should pay out on both 33 and 38.
The National Lottery, though, insists that there was only one number on the ball.
"The National Lottery would like to assure its players of the integrity of Saturday night's Lotto Plus 1 draw," it says in a statement.
"A brief reflection of light during filming caused an illusion and some players to think there were two numbers on ball 38. This was not the case."
To make sure everything's above board, it says, the weight and size of all Lotto balls - and the numbers - are strictly checked in advance of each draw.
"This process, as well as the draw itself, is independently observed by our auditors KPMG," it adds.
The ball in question was the second to be drawn, along with numbers 1, 4, 29, 45, 46 and the bonus ball, 26. But as it rolls along the tube after having been picked, it undeniably appears to have the number 33 on one side.
The illusion appears to have been caused by light shining on one side and creating a small area of glare; and a similar effect is, in fact, visible on the next number to have been drawn, ball number 45.
It's not the first time that lottery organisers have been accused of a fix. Two years ago, the head of Serbia's national lottery resigned, after the number of one of the winning balls was apparently displayed as an on-screen graphic - before it had even been drawn.
The explanation was a simple mistake. First, the number 27 was drawn - but wrongly entered as 21. The next ball to be drawn actually was 21.
There has, though, been at least one example of genuine lottery-rigging. Iowa lottery head of information security Eddie Tipton exploited his position to pre-program the lottery computer to pick certain numbers - but was caught and given ten years in jail.
Biggest UK lottery winners
Biggest UK lottery winners
Colin and Chris Weir, from Largs in Ayrshire scooped 161 million in the EuroMillions draw after several rollovers in 2011. They are the biggest British lottery winners in history.
Adrian Bayford, who won an astonishing £148m on the Euromillions with his wife Gillian, had to shut up the music shop he owns, because people targeted it with requests for money.
One British ticket won £113,019,926 in October 2010 but decided not to go public.
Car mechanic and racing driver Neil Trotter scooped a staggering £107.9 million jackpot on the Euromillions lottery in March 2014.
Dave and Angela Dawes won £101 million on the EuroMillions in 2011. It was only the third time the couple, from Wisbech, Cambridgeshire, had played the lottery. The couple are said to have since split up.
The sum was won in May 2010 but the winner kept their identity a secret.
One lucky British ticket-holder picked up a £81million EuroMillions rollover but remained anonymous.
Nigel Page and Justine Laycock from Cirencester bagged a £56 million jackpot back in February 2011. On winning the jackpot, Page said: 'I'd already checked my National Lottery account and had seen I'd won £55 on Lotto when I decided to buy two Lucky Dips for the big EuroMillions jackpot on Friday.'
One lucky winner won shy of 50 million but chose to remain anonymous.
Les and Sam Scadding from Newport, South Wales, and a syndicate of seven Liverpudlian call-centre workers shared a staggering £91 million in November 2009. Les, an unemployed mechanic, was £68 overdrawn on the day he bought his ticket, while the Liverpool syndicate only started playing EuroMillions together four months before their win.
Carrington, 22, from Stapleford in Nottingham, banked £45 million after matching all five numbers and two Lucky Stars in a EuroMillions draw in February 2012. The Iceland supervisor said she planned to marry painter fiancee Matt Topham, 22, following the Lucky Dip win.
Husband and wife Gareth and Catherine Bull have fairly modest spending plans despite their £40.6 million jackpot win in January. Speaking about what she planned to do now that she was rich, Catherine explained that she intended to use part of their winnings to replace the carpet on her upstairs landing...
Angela Kelly became one of the biggest lottery winners in UK history back in 2007, after scooping a £35 million EuroMillions jackpot. This is estimated to earn £5,000 a day in interest alone, meaning she's unlikely to ever be short of cash.
In June 2009, 74-year-old Brian Caswell got the surprise of his life when he took his lottery ticket to his local newsagent and discovered he'd won almost £25 million.
Belfast housewife Iris Jeffrey, 58, was the lucky holder of the record 20.1 million rollover lottery winning ticket back in 2004.
Jeffrey, 58, a cancer sufferer, only realised three weeks after the draw took place that she had won the jackpot after organisers Camelot pleaded for the person holding the prize ticket to come forward and claim the prize.
Stephen Smith and his wife Ida from Hemel Hempstead, Herts, won nearly 19 million in the National Lottery. Mr Smith said he would give up his winnings if he could have his health and the chance to live a longer life with his wife.