The way Owen Farrell's World Cup is going, he will do well to remember which country he is in by the time the trophy is awarded. And that is not meant flippantly. For the second consecutive match, England's captain was banjoed jaw-high by a disgraceful shoulder challenge that raised doubts about his capacity to keep absorbing such illegal hits.
Remember the time when Farrell's own tackling technique was the subject of many a Six Nations slanging match?
England's leader, who seems to have a target on his jersey out here (or, rather, on his chin) has many times been guilty of stopping opponents with "no arms" and chest or shoulders first.
Moral equivalence, though, has no place in the debate convulsing this World Cup about tackle heights and the need to avoid brain injuries.
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"Karma" can be kept in the religions file. More salient is that Farrell has twice been smashed round the jaw and twice had his head knocked backwards with sickening force.
World Rugby's laws are designed to make players tackle below neck height and to "wrap arms" rather than using shoulders as weapons. But the USA's John Quill and Argentina's Tomas Lavanini appeared to think Farrell was not covered by the tighter regulations.
Why Farrell was not given a full head injury assessment is a question the authorities will need to answer while Lavanini faces up to the shame of costing his country their chance of staying in the tournament.
From England's perspective this was the only upside of seeing Farrell on the deck again. Lavanini's removal came after TMO reviewed Owens' lenient verdict on the hit: "No foul play for me, no foul play," the referee said. Then he corrected himself, telling the perpetrator: "The law is quite clear that we look after the safety of the players. You were always high, you were leading with the shoulder and you make contact with the head of number 10 who has not come down enough from the height for me to give you anything but a red card. It is a shoulder to the head with a high degree of danger. That is my decision."
With England in this form, 14 Pumas were not going to win the set-piece "war" they had promised or disrupt George Ford's cool mastery of the No 10 position vacated by Farrell under Eddie Jones' favoured plan.
England are now in the quarter-finals and can treat Saturday's game against France as a referendum on whether they finish top or second in Pool C. At this point four years ago, they were playing for their lives. Argentina certainly helped them along the road to the quarter-finals in Oita but at the same time England have been masters of their own fate with three bonus-point wins and 119 points.
The sole mitigation for Lavanini was that Farrell was dropping slightly, with legs bent, when contact was made. But TMO gave the correct guidance and for the fifth time in this tournament a player was sent from the field. Lavanini has two reds and five yellows to his name in Test rugby and left the pitch with tears welling in his eyes.
Argentina's brutal intent had shown itself five minutes before Farrell was felled when Pablo Matera, their captain, crashed into Ben Youngs long after the ball had gone and sparked a 12th-minute melee. On days like this, you see rugby caught between the old ways and the imperative to eradicate cheap shots and thuggery. The game remains conflicted, and some match officials seem to want to keep a leg in both dimensions - past and future.
This was a game for example where Owens' empathic or chatty style failed him. He was too relaxed about Mater's tackle on Youngs and should have seen that Farrell had been endangered by Lavanini's hit (the jerk of the England player's head was the clue). Interestingly, crowds are responding to these offences with an ever-deepening gasp. The message is getting through to audiences but not always players and referees.
Nobody except Farrell can know what effect being battered twice in 10 days has had on a player who was always going to be pivotal for England. But he did miss three kicks after feeling Lavanini's shoulder along his jawline before converting a second-half George Ford try and slotting a 53rd-minute penalty.
Maybe he is fine. Maybe he is even tougher than we know. Toughness of character, however, does not offer special protection to the human brain.
As another shoving match erupted after Luke Cowan-Dickie's 78th-minute try, Farrell happened upon a sweet ending to a potentially gruesome day. He sucked on his drinks bottle then quarter-circled the ball on its tee like a scorpion. Argentina's defenders rushed at him one last time before he floated the ball over to close out a 39-10 win notable for Sam Underhill's low and legal tackling.
This being rugby, where violence is usually forgiven, Farrell then worked his way along a line of Argentina players, shaking hands. England were through and all was well with the world. But in the days to come Farrell, who lost a piece of his nose against USA, would not be human if two appalling hits failed to stalk his memory. The game has woken up to these dangers. Well, parts of it have.
• Paul Hayward is the Chief Sports Writer at the Daily Telegraph in London. He has previously written for the Guardian, the Independent and Daily Mail, and regularly appears as an analyst on Sky Sports News in the UK.