Cardiff's director of rugby Phil Davies indicated he may appeal any suspension handed down to Lloyd Williams who was shown a red card during his side's 35-24 Heineken Cup defeat to Montpellier on Sunday.
The scrum-half was dismissed by referee John Lacey for a tip tackle on Benoit Paillaugue after 25 minutes at the Arms Park, at which stage the hosts led 9-6.
The Blues were forced to play the remainder of the contest with 14 men and Davies said: "It was a bit of a rustic challenge, I think we will contest it but we will have to have a look at it.
"But I am not sure it was the right decision. It was unfortunate, in the last few weeks Lloyd has been playing really well but aside from that I thought the way we adjusted to the setback was really pleasing.
"A couple of loose kicks cost us and we did not go through the phases down in their half often enough to get extra penalties or even potentially score a try, but overall the effort and determination was fantastic."
Montpellier coach Fabien Galthie added: "The red card was important, it changed the face of the game.
"After that the referee penalised us a lot because he wanted to equalise the game.
"But the law is the law. The player knows the law and he has to respect it. It would have been the same for us.
"It is a dangerous tackle that deserved a red card."