Blood injury, my foot! Or should that be Lee Byrne's foot, which needed the removal of a boot before anybody could see any of the crimson stuff.

Or, perhaps, the foot the Ospreys shot themselves in when the bungled restoration of their international full-back, cast a shadow over their best ever win in European competition?

One newspaper has already dubbed the incident 'subgate' and has linked it with 'mudgate' (the fiasco surrounding the postponement of Sale's Guinness Premiership fixture with Wasps this season) and 'bloodgate' (the fake blood furore that got Harlequins into such a tangle last year).

All three incidents are damaging to the image of rugby. How can the sport expect to be taken seriously, they argue, when it gets itself into so many messes of its own making?

The law insisting that players with blood flowing from an open wound should be made to leave the field was a good one and originated, I believe, from a fear that infections could be passed on to other players unless a wound was staunched.

It made sense, therefore, to allow the player to be replaced while the blood was being stemmed, and to allow him back on to the field when it had been cleaned up.

In drafting the law, the IRB couldn't have had the faintest idea that it would be so open to interpretation and exploitation.

Bloodgate should have concentrated the minds of everyone at the top end of the game. It quite clearly didn't.

How could Byrne and the trainers who have attended to him have had the nerve to claim that one bleeding toe should constitute a blood injury?

How could the referee have agreed with them, knowing that if Byrne had kept his boot there would have been next to no chance of a bloody sock-encased toe posing a health risk to other players?

If referee Allan Lewis had called that correctly, he would never have found himself in the farcical situation 10 minutes later – with the game poised on a knife-edge – of trying to find out how long the Ospreys had had 16 players on the field, whether it had any material effect on the game and what punishment he should apply.

He quite rightly bawled out the Ospreys touchline official for being so keen to return Byrne to the fray that she didn't communicate properly with the assistant referee about her intentions to make the switch, or to the player who would have to make way for Byrne.

But he couldn't be absolutely sure that the Ospreys' temporary numerical advantage had a material effect on the result and he couldn't be absolutely sure that Leicester didn't also have an extra man on the pitch – as, apparently, was pointed out at the time by a sharp-eyed Ospreys player.

As with last year's 'bloodgate', the what-ifs are too awful for the game to contemplate.

What if Byrne had made a try-saving tackle during the crucial passage of play when Leicester attacked the narrow side, and Byrne could be seen at the top of the picture guarding against a sudden break or a kick-ahead.

It's naive to suggest that Leicester scrum-half Ben Youngs wasn't aware of Byrne's presence, or inhibited by it. The peripheral vision that is so essential to a top sportsman would have alerted him to the presence of an extra defender in an area of the field he might have attacked. Everybody else on the field, team-mates and opponents alike, would have adapted similarly to Byrne's presence.

Of course, there's no certainty that if Byrne hadn't been where he was, Leicester would have scored, and it 's only slightly more likely that if they had been awarded a penalty, they might have kicked the three points. And even if they had kicked the penalty, the Ospreys would still have been two points ahead and would still have been likely to win the game.

But none of that is certain, and everyone involved can thank their lucky stars that it isn't.

Rugby would be a laughing-stock if it had to rearrange a match or overrule a result because someone couldn't count.

As it is, the sport will surely think twice – if it can count that far – about the idea of rolling substitutions. Maybe it will borrow an idea from football. When one player replaces another, they pass each other. Each knows what he's doing, and so does the referee. It wouldn't take much for rugby to follow suit.