Gethin Jenkins will undergo X-rays following a heavy collision during Cardiff Blues' tense Guinness PRO14 victory over the Dragons.
The Wales record cap holder had come on from the bench when Brad Thyer was sin-binned during the first-half at Rodney Parade.
However, he did not last wrong as he was caught on the wrong side in the tackle and was taken off for a HIA.
"He had a nasty bang to the face," said Cardiff Blues head coach Danny Wilson.
"He will have an X-ray to check there is nothing broken but he is quite confident there is not.
"It is just a case now of concussion protocols he will have to go through.
"I feel for him at the moment because he is not having a huge amount of luck. There is nobody who works harder to get on the rugby field.
"Hopefully it is a minor thing and we can get him back in the next couple of games."