Forget the pneumonia. There is another kind of epidemic raging through the Hong Kong Stadium which is causing consternation amongst the fans. It is the yellow fever - the sight of referees holding up the yellow card sin-binning players for two minutes. In a bid to crack down on foul play and infringements - which officials say could lead to foul play - the International Rugby Board has told all referees to take a 'zero tolerance' approach and issued them with a set of guidelines which has led to a spate of sin-binnings over the past two days. 'It is our new policy of zero tolerance. Last year there were a number of unsavoury incidents in the series and we decided that something must be done to clean things up,' said Steve Griffiths, IRB referee's manager. 'We don't want such things cropping up again and referees have been issued guidelines on what to do,' said Griffiths. On the opening night on Friday, 12 players were sin-binned. Yesterday, an additional 32 were shown theyellow card bringing the grand total to 44. Last year the IRB met with four leading coaches - England's Joe Lydon, Gordon Tietjens of New Zealand, Australian Julian Gardener, and South Africa's Chester Williams - to try and identify the areas of concern. It was found that small infringements, like throwing the ball away or pulling the jersey of a player who did not have the ball, led to more serious acts of foul play. 'We had a video done and sent it to all the unions involved in the series. The video addressed areas like the scrum, tackle and foul play. We also briefed the referees before the start of this tournament,' said Griffiths. If players receive two yellow cards in a game, they are sent off. If they receive three yellow cards in the tournament, they will then have to appear before the IRB's judicial officer who could suspend him from any further play. The rash of yellow cards is an all-time high for Hong Kong. Last year the tournament finished with around a dozen yellow cards handed out. This number was equalled on Friday alone. Now every time a yellow card has appeared the crowds have responded by booing the decision. One critic said the game was being sanitised to such an extent that it would resemble touch rugby. More worryingly, the sin-bin could cost teams dearly in the big match-ups that will occur today. But Griffiths was confident that when the big teams met, acts of foul play would be minimal. 'We have found out that a large number of the sinbins have been against teams who do not play regularly on the series. I'm positive we will have superb and clean rugby on the final day,' he said.