Clermont hooker Benjamin Kayser has claimed it would be bad for the game to further punish Dylan Hartley for the yellow card he received during Northampton's Champions Cup defeat in France.
The Northampton No. 2 was sent to the sin bin after he struck Clermont tighthead Rabah Slimani in the face with a swinging arm during his side's 24-7 loss to the Top 14 outfit.
Although the clash left Slimani with a bloody nose, referee Ben Whitehouse decided that it was only worthy of a yellow card after reviewing the incident, deeming Hartley's actions to be "reckless but not intentional."
The England international -- who is expected to remain as captain when Eddie Jones announces his squad for the upcoming autumn internationals Thursday -- faces a nervous wait to find out whether he will be sanctioned further for the incident.
Although Clermont captain Kayser admitted that the challenge deserved punishment, he believes that an additional sentence would be harsh.
"I think a sanction was merited because a penalty is a penalty and, if he deserved yellow, it was a yellow," said the France hooker. "Should it have been a red card? No, come on.
"Rugby is rugby and, if you say that any hit on the head is a red card, there will be 25 a match. The last thing we want is to go out and start playing on the rules and to start saying [to the referee], 'It was a cheap shot.'
"We are not football. We are just here to play hard and to keep on going. I don't think it was a red card, just a yellow."
Any further penalties for Hartley would be in line with World Rugby's recent crackdown on challenges involving contact with an opponent's head. Last December, the Northampton skipper was banned for six weeks after he caught Leinster's Sean O'Brien with a swinging arm during another Champions Cup tie.
"It is a physical game and serious offences need to be dealt with harshly for the health and safety of the players," Kayser added. "But it must not be taken too far. It is about players taking it in our own hands and ensuring we do not spoil this wonderful game of ours.
"It is a sport where we are fortunate enough to be able to talk to referees and have decent relations.
"There is nothing better than a referee turning round and asking the opposition captain whether a player deserved a red card. Most of the guys would say: 'Listen, it is nothing.' We are not idiots and we are not cheats."